Genome2D is blinking something on the screen. Yay! :D
Organize renders to make them call Flixel update loop.
Flixel invokes the render's draw() method to draw the current frame.

Only FlxBlittingRender is drawing something, the FlxGenome2DRender is displaying a bunny and ignoring all state members.
Make Flixel draw things using the FlxBlittingRender.
Code is a mess, but FlxGenome2DRender is rendering! \o/

I've used placeholder code everywhere, but FlxGenome2DRender is rendering single-frame FlxSprites in simpleRender.
"complex render" (!isSimpleRender) is working.
FlxSprite seems to be working.

This is not the best approach to achieve that, but I've tried to keep changes to a minimum. This commit also differs from my original idea of implementing a render that is completely decoupled from renderable entities (e.g. FlxSprite).

I've left some hardwired rendering code in FlxSprite (see calcFrame(), for instance), but they will be removed as I progress.
Fix a few problems to make FlxText and FlxButton GPU-renderable
Tile maps are partially working!
Fix rendering at wrong position in GPU mode.
Fix camera.bgColor problem in GPU render.
Fix FlxSprite#stamp() in GPU render.
Cameras are working in GPU render (change breaks draw() signature).

I've tried my best to implement the GPU render without affecting the current drawing API, but that was not possible. The way Flixel draws entities is completely unfriendly for a GPU render using cameras. My best bet was to use render to texture to overcome the problems, but that didn't work either.

I was forced to change the draw() method to draw(c:Camera), which means the Flixel render will now invoke draw() for each entity, telling it to render to the specified camera.
Camera effects (fade and flash) are working!

It's not perfect and a little bit unpleasant since fxColorAcumulator must be reset by the GPU render, not the camera itself, but it's a start already.
Restore FlxBasic#cameras.
Camera shake effect is working.
Debug buffer to display debug stuff.

The debug buffer is based on blitting and it enables Flixel to draw dynamic graphics to the screen, such as debug lines (VIS).

The debug lines used in tilemaps are not working yet.
Debug tiles in tilemaps with GPU render.

The code is extremely ugly and it needs some serious love. It's just a prof of concept for now, but it's not good. When showing debug tiles, the framerate dropped from 30 to 20 because the tilemap is being rendered twice.

I've left several TODOs and clues to refactor the code later.
Fix debug tile drawing in blitting render.
Tweak render initialization and improve some docs.