Rewrote EZAudioPlotGL and removed EZAudioPlotGLKViewController
- Rewrote EZAudioPlotGL using GLKView for iOS and NSOpenGLView for OSX.
- Removed EZAudioPlotGLKViewController (no embedding in EZAudioPlotGL needed)
- Made EZAudioPlotGL layer-backed for OSX so you can add cocoa controls on top of it
- Merged similar OpenGL drawing calls and abstracted it to draw method available for subclasses to easily implement their own geometries