New rotation functionality.

* NAMEcL refers to a frame which is seen for the entirety of an object's left side.
* NAMEcR refers to a name which is seen for the entirety of an object's right side.
* NAMEcLcR does both sides.
* Having just a NAMEcL requires you to fill in the opposite side either with NAMEcn where n is 1 and 5 to 8 OR fill in with a NAMEcR
* Switches down the centerline of the object instead of at the ANGLE_202h interval for normal sprites.
* Characters were selected for 1) ease of use and 2) not getting in the way of adding support for zdoom's totally bananas 16-way sprite system at a later date if we so choose