Merge branch 'master' into refactor/re-gl-ize

Conflicts in:
	App/ArenaVisRep.m
	App/SceneView.m
Which have evolved into:
	App/SceneForCG.m
	App/SceneForGLK.m
	App/VisReps/InsideRingVisRep.m
	App/VisReps/OutsideRingVisRep.m
	App/VisReps/RingVisRep.m

Resolved by moving the changes into the new locations.  This makes the CG drawing work as it does on master, but not GLK without further changes/additions.
GLK positioning now matching merged-in CG positioning
Rotated the calculation for each ring by half-a-slice

This makes the circles look just a little nicer near the pixel-aligned edges (top, right, bottom, left) at a minor cost of a little more roughness at the 45°-aligned edges (TR, BR, BL, TL).

As a result:
• Removed simple calculations for ring top-inner and top-outer and circle top-point (leaving center-point as-is), as the first couple of points also need trig now.
• Slice-calc loops now start `sliceI` at -1 instead of 0, so that we calculate those first points (I know, weird math).
• And of course, half the slice's angular delta subtracted as a part of each point's angle calculation.