* preflightSleep, notifySleep, notifyDeepSleep now allow arbitrary
drivers/devices/software to register for sleep notification.
* Use the proceeding to clean up MeshRadio - now the mesh radio is more
like an independent driver that doesn't care so much about other systems
* clean up MeshService so that it can work with zero MeshRadios added.
This is a prelude to supporting boards with multiple interfaces (wifi,
extra LORA radios etc) and allows development/testing in sim with a bare
ESP32 board
* Remove remaining ESP32 dependencies from the bare simulation target
this allows running on anything that implements the arduino API
because the ESP32 implementation will be different from NRF52
to make this possible I needed to decouple knowlege about bluetooth from
our mesh service. Instead mesh service now uses the Obserable pattern
to let any interested consumer get notified of important mesh changes
(currently that is only bluetooth, but really we should do the same
thing for decoupling the GUI 'app' from the mesh service)
@girtsf would you mind reviewing my Observer changes? I haven't written
C++ code in a long time ;-)
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.
* Have state machine properly enter deep sleep based on loss of mesh and phone comms.
* Default to enter deep sleep if no LORA received for two hours (indicates user has probably left the mesh).
Signed-off-by: Kevin Hester <kevinh@geeksville.com>
