Added support for RefCounted types via lightuserdata

[Trey2k]

Changes:

• Changed the argument order for push_variant moving the name to be the first argument.
• Changed the argument order for expose_constructor moving the name to be the first argument.
• Added new metatable for mt_RefCounted.
• Added support to LuaState::pushVariant() for mt_RefCounted.
• Added support to LuaState::getVariant() for mt_RefCounted.
• Changed memory management. We now ignore Lua's garbage collector. Instead, all memory owned by the lua state is free'd at its death. This was a bi product of the change, and we may want to add support back in the future for Luas garbage collector.
• Readme and DOC info updated as well as some grammatical fixes.

[Trey2k]

Support for Lua garbage collection was added back.