Minor description rephrasing in README

Although a prototype of a game concept, this will likely never be fleshed out into a full game. "Game concept" is more accurate, and sounds classier.
Fixed an issue where the preferredFrameRate could not take effect.

The issue was that the CADisplayLink wasn't ready yet. Now if it isn't there, it's set up properly when it is, and the setters/getters for framerates report the right numbers.
Replaced all this crazy 3D rendering with some simple 2D drawing.

Right now, it has a gray background, shifting from dark to light (so that we know that it likes us). But it'll be prettier soon. Maybe.

* Deleted a lot of GLK-specific junk.
* Created SceneView, a view that does our pretty-ish gray drawing.
* Switched to calling UIView#setNeedsDisplay from the controller over drawRect: (the latter has no current CGContextRef).
Now draws a cute little circle too.

Drawing code cleaned up, UIColor retain structure fixed up, and a centred blue circle added.
App display name (for Springboard UI) changed to short-and-classy “M﹏★”.

Those are some cool unicode characters. If you don't have the retinas in your pixels, I recommend you zoom in and take a peak.
Changed my mind. Less class, more clean: “M　✦”.
Colored ring/donut/torus now visible.

A colored band representing the future valid play area is now present, thanks to the fresh & popplin ArenaVisRep. Also, drag-scrolling hacked in for debrugging and debragging.

Also prudent:
• Color presets within SceneView cleaned up; they're now readonly properties, and are instance vars instead of statics.
• ArenaVisRep draws in oranange with with difference blending. I'm leaving in the now-getting-pretty-annoying black/white BG color cycle for now just because the difforange looks pretty awesome on it. I did slow it down to 1/4× tho.
Graphics scaled to real-world (inches) size.

Clean-up and extraction are still needed, but I think it'll do okay for now.
Improved debug logging

• SDTLog prepends with file name, line number, class name, instance address, and method name
• DebugBlock (from http://stackoverflow.com/questions/8783363/ios-debugblock-macro) provides an Obj-C block that gets compiled out in non-debug builds
Cleaned up drawing code in ArenaVisRep and SceneView

• Split guessScreenPPI into screenPPI and screenPPIRetinaDisregarded, both self-memoized (rather than inside of init) and the former using the result of the later.
• GCContext scaling and translating is now done by SceneView#drawContentLayerWithin: instead of ArenaVisRep#draw (formerly drawAtPPI:forViewFocus:inContext).
	• I'm not sure if this is in opposition to an earlier design intent, but it works better, and I'll likely be splitting things out to additional classes soon anyway.
• SceneView's drawing is a little more broken down now. The UIKit-ordained drawRect: now calls three “layer” draws (drawBackLayerWithin:, drawContentLayerWithin:, and drawOverlayLayerWithin:), which are each intended to be drawn with different dimensional, effect, and optimization intents. Those then call out to (or for now, contain) drawing code.
• Cleaned up blank-line spacing in ArenaVisRep and SceneView, giving it my normal amount of breathing room (2 between most methods), and a little extra here and there for readability.
Merge branch 'master' into debug/master

For conflict below, conformed mostly to 'master' with pieces of 'debug/master' based on what was added earlier:
	MultiSpace/SceneViewController.m
Additional debug logging for SceneView#drawContentLayerWithin: