I think for collision detection in entmove.c, one needs to copy the functions and replace the x y z changes with c_move.
I think will be a good idea to have them implemented in the library as well (I am lazy), one set of commands without collision and another set with collision detection. Or maybe some sort of flag we can set in the existing functions to enable or disable collision detection. This library will be very useful for those not good with vector math ... hopefully it may be extended with other useful functions people want.
