Use the same character than in the system prompter.

Safes one keystroke when unlocking with a keyboard attached.

So far we only looked at the overall input time which is too short
to enter the PIN reliably.

Fixes #14

For now compare an N digit PIN

This uses libupower-glib

Fixes #11

This makes sure we're starting with a fresh number when switching
back to the keypad.

This makes sure the unlock process work keyboard only

Make it simpler to use phosh with a keyboard

We resize to the correct size in the layer surface's configure event.
The current code did not take multiple outputs into account anyway.

Since the g_signal_emit() is not at the very end of the function one of
the listeners might free the lockscreen widget when receiving the
"lockscreen-unlock" signal. Hold a reference to prevent being cleaned up
before being done.

This will be moved into an indicator at a later point.

Fixes #20

The lock screen now shows the current time and on upward drag it
switches to the lock screen. The lock screen then shows a keypad to
unlock the screen.

Validating the entered pin will be done in a follow up patch.

TODO in future patches:
 - slide up lock surface when swiping
 - wiggle pane a little if swipe is too soft
 - alpha blend out lock screen surface

instead of open coding lots of things

Thanks: Bob Ham