dependency fixes; use ctypesgencore.options.get_default_options()

Hi Bryan,

This is a small patch again with some more dependency fixing, plus added the use of ctypesgencore.options.get_default_options()

For some reason it also contains the function move-around you did, that's likely because of lack of git experience on my side (might have mixed up some branching/merging).

Cheers,
Csaba