Resolves KeyCode - Type reference cannot refer to a property

The interface of the property `$.ui.keyCode` uses a non-standard name `keyCode` which clashes with the property name, giving error `Type reference cannot refer to a property`. 

Changing the interface name from `keyCode` to `KeyCode` follows the interface naming convention and resolves this issue.
Merge pull request #1692 from scottmcarthur/master

Resolved: Type reference cannot refer to a property - for $.ui.keyCode

Thanks for the commit @scottmcarthur!