Added NormalizedShort4 and NormalizedShort2 to test suite.
Fixed bugs in NormalizedShort2/4 causing incompatibility with XNA.
Fixed Bgra4444 to properly clamp input values.
Fixed packing order of Bgra4444.
Added more tests for Bgra4444.
Added tests for Byte4 type.
Added Short2(), Short4(), and Bgr565() tests.
Fixed incorrect packing in Short4.
Fixed missing input clamping in Bgr565.
Merge pull request #2207 from SickheadGames/short4fix

More PackedVector Fixes
Merge branch 'develop' of git://github.com/mono/MonoGame into monogame-sdl2