Removed all "-1"s from R_PointToAngle and R_PointToAngle2, in order to allow ALL basic compass directions at the least to be given the right angle by these functions.

Note: Before this change, North and West directions would be returned as ANGLE_90-1 and ANGLE_180-1. This caused the pusher polyobjects in THZ2 to slowly move sideways as a side-effect (and probably caused similar bugs in the past too, these functions have barely been touched in a decade it turns out.)