- rename module OP_MTL_fix_all_material to OP_MTL_fix_all_materials.
- rename operator BBP_OT_fix_all_material to BBP_OT_fix_all_materials.
- rename module UTIL_naming_convension to UTIL_naming_convention.
- change some translation contexts to correspond with this change.
- move rail creation function into an individual file, UTIL_rail_creator.py
- add flip options for screw rails. this allow user to create any types of screw rail they needed.
