Launch sequence handler

[mc-cat-tty]

FSM to manage different stages of the launch, from the power-on to the landing.
Organized with different hooks (callback functions registered for a specific event):

• on_poweron -> selftest
• series of beeps if error
• send n packets to the ground station
• on_launch -> reactivate sensors
• on_max_height -> start measurements and transmission
• on_landing -> close files, turn off the fan, pause sensors (except GPS)
• on_ground -> slow down packet sending, send only GPS coordinates