Cancel on uninit

We keep track of the active ids and end them on uninit. This make sure feedbacks don't continue to run if the application quits and forgets to end a feedback.

Can be tested with CTRL-C in fbcli.

(one other thing off the list before tagging a first release).

This mixes in some unrelated changes but since i usually self merge it does not matter, if somebody else wants to have a look i'm happy to split that out.