RotoContextPrivate::renderInternal: simplify
RotoContext: work around a cairo bug
Roto: cairo antialiasing produces artifacts, use feather instead
Choice_Knob::getHintToolTipFull();: new method
RotoContext: more safety, use defines for shared strings, set hints
RotoPanel: add tooltips
RotoPanel: better tooltips
RotoContext: better help
Merge branch 'workshop' of https://github.com/MrKepzie/Natron into workshop

Conflicts:
	Global/GitVersion.h