add local type listing and searching function

[hoooonnam]

I added a function to get list of local types in file loaded in IDA.

[mrexodia]

Thanks for your contribution!

[Trass3r]

Does this + declare_c_type enable the model to refine data structures, at least in theory?

[mrexodia]

Yeah it should! The declare_c_type overwrites an existing type if you make one with the same name if I remember correctly from my experiments.