Confusion between "session_id" and "project_id" in OfrakProject

[whyitfor]

Which files would be affected?
The OfrakProject has a session_id and project_id, but currently only the session_id is used. This is confusing because both "project" and "session" ids are referenced in the code.

I propose using only the session id and adding documentation explaining what it is.

Does the proposed maintenance include non-doc string functional changes to the Python code?
This will result in changes to the OFRAK Project feature in the GUI.

Are you interested in implementing it yourself?
Yes!