Simplify keyword argument processing by switching from compile-time to run-time iteration with type erasure for default arguments.
Started adding keywords into callable.
Rename kwds to arg_list.
Started on class to convert a tuple of args from python
Add int and long builtin wrappers.
Link scratch against main library; add EUPS table file temporarily for easier development.
Fix infinite recursion problems in type wrapper.
Handle not-found registrations correctly.
Finish up args_from_python and start using it in callable.
Rework callables and keywords to start on overloading support.

Removed now-obsolete keywords test; need to replace it with something better once callable is finished.
Temporarily removed call to args_from_python; need to add args_from_python base so we can return it polymorphically.