#8 AI ships jitter

[Ben Lard]

The AI ships jitter alot, apparently executing a rapid
series of turnleft,turnright,turnleft,turnright
because the rotation is limited to degree accuracy and
they are aiming at something between degrees. Thus it
needs to detect if changing direction by a degree will
overshoot or not. A related problem is thrust - the
computer sometimes only thrusts for a frame, which is
very un-human-like, especially if it's every other
frame. If we want it to simulate a human, we need to
have a minimum quanta of thrust time.