Update template style
Refactor and use grid() instead of pack()
Rename source_types.py to substyles.py
Update abstract method Substyle.setup_gui
Make things work again after 01904c8299
Extra lines in the name of PEP 8, rename some parameters for consistency
GUI work
Fetch styles and substyles for GUI
Update class diagram
Remove venv from repo
Start working toward outputting RTF

Small fixes and improved encapsulation
Add self.__id to Substyle
GUI: Select style and update form_frame accordingly
Add LICENSE: MIT
Add license info to core modules

Basic module level documentation
Refactor: Substyle: make generate_id() a method rather than a module level function
Update README.md
Merge branch 'dev'