Merge pull request #4067 from ethereum/050

[BREAKING] Version 0.5.0

docs/contracts.rst

@@ -802,7 +802,7 @@ as topics. The event call above can be performed in the same way as
             log3(
                 bytes32(msg.value),
                 bytes32(0x50cb9fe53daa9737b786ab3646f04d0150dc50ef4e75f59509d83667ad5adb20),
-                bytes32(msg.sender),
+                bytes32(uint256(msg.sender)),
                 _id
             );
         }

docs/types.rst

@@ -762,7 +762,7 @@ Members
             // Create a dynamic byte array:
             bytes memory b = new bytes(200);
             for (uint i = 0; i < b.length; i++)
-                b[i] = byte(i);
+                b[i] = byte(uint8(i));
             return b;
         }
     }
@@ -975,6 +975,15 @@ cut off::
     uint32 a = 0x12345678;
     uint16 b = uint16(a); // b will be 0x5678 now
 
+Since 0.5.0 explicit conversions between integers and fixed-size byte arrays
+are only allowed, if both have the same size. To convert between integers and
+fixed-size byte arrays of different size, they first have to be explicitly
+converted to a matching size. This makes alignment and padding explicit::
+
+    uint16 x = 0xffff;
+    bytes32(uint256(x)); // pad on the left
+    bytes32(bytes2(x)); // pad on the right
+
 .. index:: ! type;deduction, ! var
 
 .. _type-deduction: