Refactor gocamgen to make it usable in GO pipeline (ontobio)

[dustine32]

Right now a lot of code is sitting in files outside of the module package folder gocamgen making it difficult to generate models outside of this repo:

filter_rule.py
gen_models_by_gene.py
gpad_extensions_mapper.py
rdflib_sparql_wrapper.py
triple_pattern_finder.py
utils.py

I need to move and rehook up this code so that everything is accessible and functioning for projects that import gocamgen.

This will be fun.