WIP: Allow to unfold keyboard to allow for non-numeric passwords
Since this comes up ever so often this MR does:
- add a keyboard button to the lock screen dial pad that unfolds the keyboard on press
- allow arbitrary text input
- hide keyboard when we time out and switch back to the lock screen
Design issues
- does this fly at all?
- should we hide the keypad with a revealer when the keyboard is folded out?
- should the label change from passcode to passord ?
TODOs (mostly mechanical):
- replace keypad-button by regular buttons
- adjust d/copyright
- add to docs
- add keypad tests from libhandy too
/cc @tobias.bernard
Closes: #97