Replaced NSTimer with CADisplayLink.
Changed Tick() from public to internal.
Simplified math, added comment.
Merge branch 'develop' into ReplaceNSTimer
Cleanup of documentation for SoundEffectInstance. Removed unnecessary hold on the parent SoundEffect reference. Removed a duplicate initialization of the source buffer. Changed the use of Math.exp in the pitch conversion code to use Math.pow so that it can be understood better.
Merge pull request #1390 from totallyeviljake/ISSUE_1386_R1

Cleanup of documentation for SoundEffectInstance and misc code cleanup.
Merge pull request #1384 from SickheadGames/ReplaceNSTimer

Replaced NSTimer with CADisplayLink.
Fix rendertarget rendering (OpenGL)
Merge branch 'develop' into InfiniteFlight

Conflicts:
	MonoGame.Framework/Graphics/GraphicsDevice.cs
	MonoGame.Framework/iOS/iOSGameView.cs