#63 Back Turret movement is poorly controlled

[Cor'e =)]

The controls for the moving the Back Turret are not fine enough, there are rather big jumps in movement, this coupled with the graphics of tail-eating AI controlled enemies makes the Back Turret a problem to use. Even when i'm using the tractor i must keep going front and back (F5,F5,F5,...) to position the ship to finely re-position the Turret. IMO, the Turret movements are too coarse.