Merge branch 'new_new_spriteframe_angle' into 'master'

NAMEcLcR sprite angle loading, take 2

HEY LOOK, A NEW SPRITE LUMP LOADING FEATURE (which isn't that new since this merge request description is literally copypasted from the one for public next)

 * NAMEcL refers to a frame which is seen for the entirety of an object's left side. (ie - in 2d mode, facing to the left relative to the camera)
 * NAMEcR refers to a name which is seen for the entirety of an object's right side. (ie - in 2d mode, facing to the right relative to the camera)
 * NAMEcLcR does both sides, duh. I didn't break reflection.
 * Having just a NAMEcL requires you to fill in the opposite side either with NAMEcn where n is 1 and 5-8 OR a NAMEcR OR a NAMEc0
 * Having just a NAMEcR requires you to fill in the opposite side either with NAMEcn where n is 1-5 OR a NAMEcL OR a NAMEc0
 * Switches down the centerline of the object instead of at the ANGLE_202h interval for normal sprites. Has a very small window where you can see a NAMEc1 and NAMEc5 if you only use one of NAMEcL or NAMEcR down one side.
 * The specific symbols selected for this were selected for 1) ease of mental understanding (Left, Right) 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, which only goes up to G

totally makes sense for stuff like NiGHTS stuff, Axis2D stuff, and maybe if SRB1 survives the chopping block in some shape or form it can take advantage of that too

See merge request !33