As some tiltrotor systems need a certain tilt angle of their motors in oder to spin up freely,
this commit introduces an additional parameter VT_TILT_SPINUP and sets the motor tilt to
this value if disarmed or within 1s since arming.
The spinup consists of 2 phases:
1st phase fixed tilt (duration hardcoded to 1s)
2nd phase transition from spinup tilt to multicopter tilt (hardcoded to 0.5s)
Signed-off-by: Silvan Fuhrer <silvan@auterion.com>
