Various fixes and formatting chores (#885)

* fix: clean up solium linting errors

* fix: make various contracts natspec compliant

* fix: this.balance deprecated; convert to address(this).balance

* fix: contract.call deprecated and switch to gasleft()

* fix: ignore empty block rule project-wide

* fix: add ignore cases for the rest of the linting warnings

contracts/mocks/ERC223TokenMock.sol

@@ -21,6 +21,7 @@ contract ERC223TokenMock is BasicToken {
   {
     transfer(_to, _value);
     bool isContract = false;
+    // solium-disable-next-line security/no-inline-assembly
     assembly {
       isContract := not(iszero(extcodesize(_to)))
     }

contracts/mocks/ERC721ReceiverMock.sol

@@ -14,9 +14,21 @@ contract ERC721ReceiverMock is ERC721Receiver {
     reverts = _reverts;
   }
 
-  function onERC721Received(address _address, uint256 _tokenId, bytes _data) public returns(bytes4) {
+  function onERC721Received(
+    address _address,
+    uint256 _tokenId,
+    bytes _data
+  )
+    public
+    returns(bytes4)
+  {
     require(!reverts);
-    emit Received(_address, _tokenId, _data, msg.gas);
+    emit Received(
+      _address,
+      _tokenId,
+      _data,
+      gasleft() // msg.gas was deprecated in solidityv0.4.21
+    );
     return retval;
   }
 }

contracts/mocks/MessageHelper.sol

@@ -15,6 +15,7 @@ contract MessageHelper {
   }
 
   function call(address to, bytes data) public returns (bool) {
+    // solium-disable-next-line security/no-low-level-calls
     if (to.call(data))
       return true;
     else

contracts/mocks/ReentrancyAttack.sol

@@ -4,6 +4,7 @@ pragma solidity ^0.4.21;
 contract ReentrancyAttack {
 
   function callSender(bytes4 data) public {
+    // solium-disable-next-line security/no-low-level-calls
     require(msg.sender.call(data));
   }
 

contracts/mocks/ReentrancyMock.sol

@@ -27,7 +27,8 @@ contract ReentrancyMock is ReentrancyGuard {
     bytes4 func = bytes4(keccak256("countThisRecursive(uint256)"));
     if (n > 0) {
       count();
-      bool result = this.call(func, n - 1);
+      // solium-disable-next-line security/no-low-level-calls
+      bool result = address(this).call(func, n - 1);
       require(result == true);
     }
   }