ofCairoRenderer: fix for cairo blend modes not existing in older versions
Merge pull request #1954 from arturoc/bugfix-cairoblend

ofCairoRenderer: fix for cairo blend modes not existing in older versions
ofCairoRenderer: fix flipY
Merge pull request #1957 from arturoc/bugfix-cairo

ofCairoRenderer: fix flipY
Merge branch 'develop' of https://github.com/openframeworks/openFrameworks.git into develop
ofCairoRenderer: fix save to image
ofRectangle: fix operator+
ofGLRenderer: don't multiply path color by current color
Merge branch 'develop' of https://github.com/openframeworks/openFrameworks.git into develop