add mat3 uniform setter in ofShader
add note recommending 4x4 mat for shader uniform
Merge branch 'master' into feature-shader-uniform-mat3
Merge branch 'master' into feature-shader-uniform-mat3

Conflicts:
	libs/openFrameworks/gl/ofShader.h
directly access ofMatrix3x3 member when setting uniform
Merge pull request #3177 from admsyn/feature-shader-uniform-mat3

Add setter for mat3 uniforms in ofShader
fix int being used where it should be ofWindowMode

in many places, particularly setupOpenGL() and getWindowMode() methods, as well as
variables to store windowMode, the ofWindowMode enum was not being used as the type
fix RPI install_dependencies
update CHANGELOG.md for ofWindowMode, fixes #3187
Merge pull request #3189 from acarabott/bugfix-ofWindowMode

Bugfix of window mode
Merge branch 'master' of github.com:openframeworks/openFrameworks into feature-YUV