ofxiPhone - Move openGL to its own thread

Related forum post: http://forum.openframeworks.cc/index.php/topic,7053.0.html

From what I understand, it's best to leave the mainThread for UIKit elements and move openGL and other things to another thread. Currently, if there's a lot of drawing then the UIKit elements are delayed and can even pause the update/draw methods entirely. Moving the drawing to it's own thread should help with this.

I'm still testing, but this looks like it could be a good candidate for core integration. It has examples of threaded, single (what we currently use), and GCD (which I think is iOS 4.0 only) openGL implementation: https://github.com/Volcore/LimbicGL In my early tests, it does fix any pausing of the update/draw with the threaded example (haven't tried the others). I could use some help though trying to integrate this into OF properly.

The main example classes are here: https://github.com/Volcore/LimbicGL/tree/master/limbicgl/drivers

Start with the related forum post and the LimbicGL repository, especially the example classes under limbicgl/drivers. Compare its threaded, single-threaded, and GCD implementations with openFrameworks' iPhone rendering entry points. Done means a core integration that preserves drawing behavior while preventing heavy rendering from pausing UIKit and update/draw activity.