[FNA] "ASCII text" File Format - Graphics, Take 2

I didn't realize the last pull request included some files in exempt subdirectories.
Merge pull request #164 from 3vi1/monogame-sdl2

[FNA] "ASCII text" File Format - Graphics, Take 2
Remove exec properties from source files
Merge branch 'monogame-sdl2' into mgsdl2-glshader