* Break out debug screen to a separate class and make it thread-safe.
* Break out power state to a separate class.
* Show battery voltage, charging & USB status on debug screen.
* Show GPS lock / no lock
* Fix an off-by-one that I introduced earlier in `drawRows`.
Work towards separating out how Screen interacts with other stuff.
* `Screen` should now be thread-safe. All commands to it are put in a
queue and handled in `doTask` from the `loop()` task.
* Break dependency from `BluetoothUtil` to `Screen` by changing the
pairing request into a callback.
* All accesses to screen now happen through the class.
* Fix `drawRows` so that the text scrolls along with frame animations.
* Remove example code that wasn't used.
* `Lock`: trivial wrapper for FreeRTOS binary semaphores
* `LockGuard`: RAII wrapper for using `Lock`
* `printThreadInfo`: helper for showing which core/FreeRTOS task we are
running under
* Suppress warnings about conflicting library names in platformio.ini by
explicitly picking the libraries by id that we want.
* fix unused static function warning by making it not static ;)
* declare arduino-fsm as dependency for BluetoothOTA. Hopefully this
fixes the CI builds?
Tested: `pio run` builds.
Girts Folkmanis
