update sdl2
Content/ContentReaders/: Add #regions
Content/: Add #regions
Merge pull request #179 from meklu/monogame-sdl2

[FNA] Add #regions to Content/
rootDir.txt patch, updated for post-region'd format.
I doubled doubled an assignment.
Merge pull request #180 from 3vi1/monogame-sdl2

rootDir.txt patch, updated for post-region'd format.
[FNA] #146 - adding regions to ./
Merge pull request #181 from extrahotchilipowder/monogame-sdl2

[FNA] #146 - adding regions to ./
Fix Device Exception namespaces
Merge branch 'monogame-sdl2' into mgsdl2-glshader