Add initial implementation of the Serializer and Deserializer classes to the scripting environment.

This commit is also the beginning of the implementation of the new scripting structure. The new
structure uses "GT" as the primary namespace, with all FFI functions being in the GT.FFI namespace.
A few changes to the scripting library:

 - The general extended library has been moved into the GT namespace.
 - Added set theory operations (union, intersect, difference) to the GT.table library.