Add option to clear all state
I wanted to add a password and setup autolock but somehow the app already thought I would have a password. Thus, I could neither set a password (because I wouldn't know what to write there) nor could I unlock after restarting the app.
I don't know why the state got corrupted but I needed to invoke keyring.clear()
manually in Python to fix it. It would be good to have this if people forget their password or the app simply has a bug.