Fixes & Performance

Fixed meta methods being passed self twice.
Fixed __concat not using tostring.
Fixed mistake in extends() regex.
Fixed missing string.format in error message.
Fixed trailing nil trimming.
Improved performance by no longer adding __gc proxies to classes that have no finalizer.
Improved performance by no longer copying helper functions into each class.
Improved performance by no longer copying static member values into instances.
Replaced finals with constants.