Added ImageKey unit test
Merge branch 'workshop' of https://github.com/MrKepzie/Natron into workshop
Merge branch 'workshop' of https://github.com/MrKepzie/Natron into workshop
Cleaner code in OfxHost to instantiate the OfxEffectInstance, it will
be easier to mock this class.
Also tweaked the abortRendering() function so it can be blocking/ non
blocking