Scratchattach

- Fixed `project.studios()` function

- Added `studio.set_thumbnail(file="filename")` method
- Added `project.set_json(json_data)` method

- Changed module names (removed _ charaters from the filenames of the files in /scratchattach) in order to document the project with sphinx
- Added sphinx documentation (WIP): https://scratchattach.readthedocs.io/en/latest/
- Added comments to code