Implemented automatic maneuvers, 2-way safety, pilot and PC override, engine control during maneuver

This reverts commit 0c81a19decde6ddfe4ce87c34c762ea15fd3ab09.

But fix the two crucial problems:
- When to begin the ramp?
There's a calculation now for the velocity ramp initial value
such that the resulting thrust is zero at the beginning.
- When to end the ramp?
The ramp is applied to the upwards velocity constraint and it
just ramps from the initial value to the velocity constraint
which is applied during flight. Slower/going down is always possible.