Fixed ImageView context scoping.
Fixed ImageView context scoping.

It wasn't using the right context when evaluating the various colour samplers. The fix continues the tradition of just shoving more and more stuff into the one monolithic class - this needs to stop.

Fixes #1124.

andrewkaufman/gaffer,boberfly/gaffer,boberfly/gaffer,chippey/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,boberfly/gaffer,cedriclaunay/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,ivanimanishi/gaffer,appleseedhq/gaffer,goddardl/gaffer,lucienfostier/gaffer,boberfly/gaffer,andrewkaufman/gaffer,chippey/gaffer,goddardl/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,goddardl/gaffer,appleseedhq/gaffer,goddardl/gaffer,lucienfostier/gaffer,ImageEngine/gaffer,hradec/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,hradec/gaffer,johnhaddon/gaffer,chippey/gaffer,appleseedhq/gaffer,cedriclaunay/gaffer,lucienfostier/gaffer,GafferHQ/gaffer,chippey/gaffer,andrewkaufman/gaffer,cedriclaunay/gaffer,ivanimanishi/gaffer,ivanimanishi/gaffer,cedriclaunay/gaffer,hradec/gaffer,hradec/gaffer,johnhaddon/gaffer,ivanimanishi/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,hradec/gaffer,johnhaddon/gaffer