OP-1379 add base types for colour, Initial ext rgb led api definition
OP-1379 - initial version of external led sequencer implemented in notification lib.
Alert overlay not working yet.
OP-1379 - Split pios_ws2811.h in config and public api header
OP-1379 - Split simple notification and external lednotifications libraries
OP-1379 - Initial Notify module. Supports:
1) predefined seqences associated with each flightmode. 2) fixed table with alarm index and assciated led warn/error sequences/repetition rate.
OP-1379 - add unit testing
OP-1379 - Various fixes and additions

- Support blocks of led for notification (that is a certain number of leds between a min and a max index);
- Fix an issue with bogus colours on fast updates at LED N°0.
- Add NOTIFY_SEQUENCE_NULL to skip handling a specific alarm status;
- Adjust sequences and add Config and Receiver Alarms;
- fix issue with Alarm trigger/repetition;
- Enables Notify module only if a WS281x output is enabled.
- Add some documentation for sequence/alarm definitions (sequences.h)
- Make sequences more coherent. All GPS related info are now shown in green.
- Revert to original blinking rate for onboard led
- add Notify on DiscoveryF4Bare target
OP-1440 - Change timing slightly to support also WS2812B
OP-1379 - Rebuild and simplify the queuing mechanism
OP-1499 - Replay the configuration sequence in case of gps disconnection, add retry logic in case of errors
OP-1379 - Prevent loosing any update to background notification and notifications with priority higher than current
OP-1499 - CFG-CFG mask was incorrect (nav is 0x02, not 0x01)
OP-1499 - Failed Autoconfig will raise an Error Alarm. When AC does start it will reset any previous ack. Force update to Autoconfig Status in GPSPositionSensor UAVO. Add a small pause between each config step
OP-1379 - Clear output pin at the end of dma cycle
Merge remote-tracking branch 'origin/amorale/OP-1379_ext_led_notification_module_new' into next

Conflicts:
	Makefile
	flight/targets/boards/discoveryf4bare/firmware/Makefile
	flight/targets/boards/revolution/firmware/Makefile
Merge remote-tracking branch 'origin/amorale/OP-1499_autoconfig_retries' into next