bump solc to 0.5.14

chainId implementation (commented out for now)

improve events

move safeTransfer in UniswapV2

tweak error messages

contracts/libraries/Math.sol

@@ -1,18 +1,24 @@
-pragma solidity 0.5.13;
+pragma solidity 0.5.14;
 
 library Math {
     function min(uint x, uint y) internal pure returns (uint z) {
-        return x <= y ? x : y;
+        z = x <= y ? x : y;
+    }
+
+    function clamp112(uint y) internal pure returns (uint112 z) {
+        z = y <= uint112(-1) ? uint112(y) : uint112(-1);
     }
 
     function sqrt(uint y) internal pure returns (uint z) {
-        if (y == 0) return 0;
-        else if (y <= 3) return 1;
-        uint x = (y + 1) / 2;
-        z = y;
-        while (x < z) {
-            z = x;
-            x = (y / x + x) / 2;
+        if (y > 3) {
+            uint x = (y + 1) / 2;
+            z = y;
+            while (x < z) {
+                z = x;
+                x = (y / x + x) / 2;
+            }
+        } else if (y != 0) {
+            z = 1;
         }
     }
 }

contracts/libraries/SafeMath.sol

@@ -1,17 +1,15 @@
-pragma solidity 0.5.13;
+pragma solidity 0.5.14;
 
 library SafeMath {
     function add(uint x, uint y) internal pure returns (uint z) {
         require((z = x + y) >= x, "ds-math-add-overflow");
     }
+
     function sub(uint x, uint y) internal pure returns (uint z) {
         require((z = x - y) <= x, "ds-math-sub-underflow");
     }
+
     function mul(uint x, uint y) internal pure returns (uint z) {
         require(y == 0 || (z = x * y) / y == x, "ds-math-mul-overflow");
     }
-
-    function clamp112(uint y) internal pure returns (uint112 z) {
-        z = y <= uint112(-1) ? uint112(y) : uint112(-1);
-    }
 }

contracts/libraries/UQ112x112.sol

@@ -1,9 +1,9 @@
-pragma solidity 0.5.13;
+pragma solidity 0.5.14;
 
 library UQ112x112 {
     uint224 constant Q112 = 2**112;
 
-    // encode a uint112 as a UQ112.112 fixed point number s.t. `y := y_encoded / 2**112` (i.e. with a Q112 denominator).
+    // encode a uint112 as a UQ112.112 fixed point number s.t. `y := z / 2**112`
     function encode(uint112 y) internal pure returns (uint224 z) {
         z = uint224(y) * Q112; // never overflows
     }