Start on Android fast app resume.

Ref: http://forums.xamarin.com/discussion/621/androidgameview-pause-without-losing-gl-context/p2
Move DeviceResetting to when the Context is lost, which is where it should be now. Fast app resume works!

Fixes #2600
Add a listener for ScreenSize changes too so we get killed less often, requires building with SDK 3.2+ (4.0+ with Xamarin)

ref http://forums.xamarin.com/discussion/comment/60864/#Comment_60864
Added Protobuild definitions for Test projects.
Fixed internals reference.
Removed old Assets project.
Removed old Test projects and solutions.
Fixed asset path.
Ignored Test csprojs.
Tests are now built as part of the desktop platforms.
SDL2# update
[IDE] Fixed path issue with mdtool
Merge pull request #2783 from dellis1972/mdtoolfix

[IDE] Fixed path issue with mdtool
Merge remote-tracking branch 'origin/develop' into android-fast-app-resume
Merge pull request #2753 from danzel/android-fast-app-resume

Android fast app resume
Merge branch 'develop' into prototest
Fixed effect content paths.
Added content references directly into XNA project.
Removed reference to old asset project.
Fixed NUnit references for Mac and Linux.