Major performance improvements to Note generation. Down from 2.5 seconds to under 1.

Fixed an issue on Android causing the back button to enable at incorrect times.

Improved the suspend / resume flow for the application on Android.

Added profiler instrumentation.

PlatformBaseUI.cs
Added an Init() allowing pre-loading of certain UI resources.

DroidLabel
DroidTextLabel
Added a font manager for caching loaded fonts.

DroidRevealLabel
DroidFadeTextView
Use a static RGBAMask as the source for generating per-label masks.

Profiler
Added basic profiler instrumentation