Tweak render initialization and improve some docs.
Rename render methods to mimic BitmapData.

Several method in the FlxRender class were renamed to better mimic BitmapData method names. I did that to make the new rendering pipeline look more similar to the old one Flixel was using.
Refactor FlxCamera and add FlxTexture.

The FlxCamera code is simpler and easier to understand regarding the GPU rendering. I've added the FlxTexture class that abstracts the concept of graphics (Bitmap or GPU texture).

FlxCamera should be tweaked in the future to use screen.texture instead of bgTexture. It should save some memory and performance.
Tweak render check.
Re-factor and code clean up for FlxSprite.
Re-factor and code clean up for tilemaps.
Rename properties in Genome render to follow Flixel conventions.
Refactor and document the main rendering look of FlxGenome2DRender.
Re-factor and code clean up for render's copyPixels().
Code clean up for render's draw() method and small bugfix for FlxSprite rotation.
Code clean up and small tweaks for render's drawDebug().
Tweak docs and param names to match Flixel naming convention.
Use FlxTexture instead of GTexture in the render API.
GPU render is able to log error messages when init fails.
Code clean up.
Small tweaks (code and docs).
Merge new GPU render into dev branch.