fix_move.cpp with a couple useful commands.

I changed fix_move.cpp to have a two new commands: linearspin and spin. spin fixes omega without velocity, and has the same syntax as linear. Linearspin fixes both velocity and rotation, and has 6 parameters (vx vy vz wx wy wz).

NOTE: spin hasn't been tested (although it was a simple change and probably works).

I found these useful in real-life situations.