v1.2

It has been long overdue. Let's serialize the world!

Some important changes since 1.1:

• Can serialize metatables now (optionally disabled with bitser.includeMetatables)
• Added an extension API
• Removed support for cdata, which was just too buggy to hold on. More robust support would probably need to depend on ffi-reflect, which is best done by an extension library

Version 1.1: bitser now supports cdata

After solving issue #14, it seemed to be time to do an actual versioned release. Let's serialize the world!