Unify code comments style. (#1603)

* Updated code style to no more than120 characters per line.

* Unify code comments style with Doxygen-style tags.

contracts/crowdsale/distribution/RefundableCrowdsale.sol

@@ -6,8 +6,8 @@ import "../../payment/escrow/RefundEscrow.sol";
 
 /**
  * @title RefundableCrowdsale
- * @dev Extension of Crowdsale contract that adds a funding goal, and the possibility of users getting a refund if goal
+ * @dev Extension of Crowdsale contract that adds a funding goal, and the possibility of users getting a refund
- * is not met.
+ * if goal is not met.
  *
  * Deprecated, use RefundablePostDeliveryCrowdsale instead. Note that if you allow tokens to be traded before the goal
  * is met, then an attack is possible in which the attacker purchases tokens from the crowdsale and when they sees that

contracts/drafts/TokenVesting.sol

@@ -12,9 +12,9 @@ import "../math/SafeMath.sol";
  */
 contract TokenVesting is Ownable {
     // The vesting schedule is time-based (i.e. using block timestamps as opposed to e.g. block numbers), and is
-    // therefore sensitive to timestamp manipulation (which is something miners can do, to a certain degree). Therefore,
+    // therefore sensitive to timestamp manipulation (which is something miners can do, to a certain degree).Therefore,
-    // it is recommended to avoid using short time durations (less than a minute). Typical vesting schemes, with a cliff
+    // it is recommended to avoid using short time durations (less than a minute). Typical vesting schemes, with a
-    // period of a year and a duration of four years, are safe to use.
+    // cliff period of a year and a duration of four years, are safe to use.
     // solhint-disable not-rely-on-time
 
     using SafeMath for uint256;

contracts/introspection/ERC165.sol

@@ -9,7 +9,7 @@ import "./IERC165.sol";
  */
 contract ERC165 is IERC165 {
     bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
-    /**
+    /*
      * 0x01ffc9a7 ===
      *     bytes4(keccak256('supportsInterface(bytes4)'))
      */

contracts/introspection/ERC165Checker.sol

@@ -10,7 +10,7 @@ library ERC165Checker {
     bytes4 private constant _INTERFACE_ID_INVALID = 0xffffffff;
 
     bytes4 private constant _INTERFACE_ID_ERC165 = 0x01ffc9a7;
-    /**
+    /*
      * 0x01ffc9a7 ===
      *     bytes4(keccak256('supportsInterface(bytes4)'))
      */

contracts/mocks/ERC165/ERC165InterfacesSupported.sol

@@ -4,6 +4,7 @@ import "../../introspection/IERC165.sol";
 
 /**
  * https://github.com/ethereum/EIPs/blob/master/EIPS/eip-214.md#specification
+ * From the specification:
  * > Any attempts to make state-changing operations inside an execution instance with STATIC set to true will instead
  * throw an exception.
  * > These operations include [...], LOG0, LOG1, LOG2, [...]
@@ -13,7 +14,7 @@ import "../../introspection/IERC165.sol";
  */
 contract SupportsInterfaceWithLookupMock is IERC165 {
     bytes4 public constant INTERFACE_ID_ERC165 = 0x01ffc9a7;
-    /**
+    /*
      * 0x01ffc9a7 ===
      *     bytes4(keccak256('supportsInterface(bytes4)'))
      */

contracts/token/ERC20/ERC20Burnable.sol

@@ -17,8 +17,8 @@ contract ERC20Burnable is ERC20 {
 
     /**
      * @dev Burns a specific amount of tokens from the target address and decrements allowance
-     * @param from address The address which you want to send tokens from
+     * @param from address The account whose tokens will be burned.
-     * @param value uint256 The amount of token to be burned
+     * @param value uint256 The amount of token to be burned.
      */
     function burnFrom(address from, uint256 value) public {
         _burnFrom(from, value);

contracts/token/ERC20/ERC20Pausable.sol

@@ -6,7 +6,7 @@ import "../../lifecycle/Pausable.sol";
 /**
  * @title Pausable token
  * @dev ERC20 modified with pausable transfers.
- **/
+ */
 contract ERC20Pausable is ERC20, Pausable {
     function transfer(address to, uint256 value) public whenNotPaused returns (bool) {
         return super.transfer(to, value);

contracts/token/ERC721/ERC721.sol

@@ -64,7 +64,7 @@ contract ERC721 is ERC165, IERC721 {
     /**
      * @dev Gets the owner of the specified token ID
      * @param tokenId uint256 ID of the token to query the owner of
-     * @return owner address currently marked as the owner of the given token ID
+     * @return address currently marked as the owner of the given token ID
      */
     function ownerOf(uint256 tokenId) public view returns (address) {
         address owner = _tokenOwner[tokenId];
@@ -125,7 +125,7 @@ contract ERC721 is ERC165, IERC721 {
     /**
      * @dev Transfers the ownership of a given token ID to another address
      * Usage of this method is discouraged, use `safeTransferFrom` whenever possible
-     * Requires the msg sender to be the owner, approved, or operator
+     * Requires the msg.sender to be the owner, approved, or operator
      * @param from current owner of the token
      * @param to address to receive the ownership of the given token ID
      * @param tokenId uint256 ID of the token to be transferred
@@ -142,8 +142,7 @@ contract ERC721 is ERC165, IERC721 {
      * which is called upon a safe transfer, and return the magic value
      * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
      * the transfer is reverted.
-     *
+     * Requires the msg.sender to be the owner, approved, or operator
-     * Requires the msg sender to be the owner, approved, or operator
      * @param from current owner of the token
      * @param to address to receive the ownership of the given token ID
      * @param tokenId uint256 ID of the token to be transferred
@@ -158,7 +157,7 @@ contract ERC721 is ERC165, IERC721 {
      * which is called upon a safe transfer, and return the magic value
      * `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`; otherwise,
      * the transfer is reverted.
-     * Requires the msg sender to be the owner, approved, or operator
+     * Requires the msg.sender to be the owner, approved, or operator
      * @param from current owner of the token
      * @param to address to receive the ownership of the given token ID
      * @param tokenId uint256 ID of the token to be transferred
@@ -172,7 +171,7 @@ contract ERC721 is ERC165, IERC721 {
     /**
      * @dev Returns whether the specified token exists
      * @param tokenId uint256 ID of the token to query the existence of
-     * @return whether the token exists
+     * @return bool whether the token exists
      */
     function _exists(uint256 tokenId) internal view returns (bool) {
         address owner = _tokenOwner[tokenId];
@@ -262,7 +261,7 @@ contract ERC721 is ERC165, IERC721 {
      * @param to target address that will receive the tokens
      * @param tokenId uint256 ID of the token to be transferred
      * @param _data bytes optional data to send along with the call
-     * @return whether the call correctly returned the expected magic value
+     * @return bool whether the call correctly returned the expected magic value
      */
     function _checkOnERC721Received(address from, address to, uint256 tokenId, bytes memory _data)
         internal returns (bool)

contracts/token/ERC721/ERC721Enumerable.sol

@@ -22,7 +22,7 @@ contract ERC721Enumerable is ERC165, ERC721, IERC721Enumerable {
     mapping(uint256 => uint256) private _allTokensIndex;
 
     bytes4 private constant _INTERFACE_ID_ERC721_ENUMERABLE = 0x780e9d63;
-    /**
+    /*
      * 0x780e9d63 ===
      *     bytes4(keccak256('totalSupply()')) ^
      *     bytes4(keccak256('tokenOfOwnerByIndex(address,uint256)')) ^

contracts/token/ERC721/ERC721Metadata.sol

@@ -15,7 +15,7 @@ contract ERC721Metadata is ERC165, ERC721, IERC721Metadata {
     mapping(uint256 => string) private _tokenURIs;
 
     bytes4 private constant _INTERFACE_ID_ERC721_METADATA = 0x5b5e139f;
-    /**
+    /*
      * 0x5b5e139f ===
      *     bytes4(keccak256('name()')) ^
      *     bytes4(keccak256('symbol()')) ^

contracts/token/ERC721/ERC721Pausable.sol

@@ -6,7 +6,7 @@ import "../../lifecycle/Pausable.sol";
 /**
  * @title ERC721 Non-Fungible Pausable token
  * @dev ERC721 modified with pausable transfers.
- **/
+ */
 contract ERC721Pausable is ERC721, Pausable {
     function approve(address to, uint256 tokenId) public whenNotPaused {
         super.approve(to, tokenId);

contracts/token/ERC721/IERC721Receiver.sol

@@ -18,7 +18,7 @@ contract IERC721Receiver {
      * @param from The address which previously owned the token
      * @param tokenId The NFT identifier which is being transferred
      * @param data Additional data with no specified format
-     * @return `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
+     * @return bytes4 `bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"))`
      */
     function onERC721Received(address operator, address from, uint256 tokenId, bytes memory data)
     public returns (bytes4);