Add & use basic Rmilec RX support.
Servo as debug output only if available.
Move everything model specific to config-tri.h.

Move functions around, change some defines to variables, etc., etc.
Basic I2C ESC-communication support.

See https://github.com/balrog-kun/tgy for more information about the
capabilities and the protocol.
Quadcopter configuration.
Basic LPC1343 ADC support.
Measure Rmilec's RSSI on ADC input 7, send to OSD.
Longer RX loss emergency timeouts.
Yaw == heading (0 is north).  Assume mag good at boot.
Interrupt-based async LPC1343 UART Tx, cleanup.
Don't forget to shift REVERSE_MASK right.