When the screen switches, the full screen needs to be refreshed for the
hardware scrolling to work. This was enforced with backgroundLabels, but
is simpler to do with a rounder function.
When a passkey is displayed, screen on or off, and another
passkey is displayed the screen may become scrambled. Fix
the issue by insuring the whole screen is drawn every time.
This commit adds the following:
Passkey pairing - passkey is displayed on watch
Swipe down to clear passkey screen
Connection encryption
Connection bonding
Automatic reconnects to a bonded peripheral
Trusted device on Android
Note that persisting the bond between reboots is NOT included in
this commit. Therefore, rebooting the watch will cause reconnect failures.
You must delete the bond from the phone to reconnect/pair.
