Fixed SceneView expansion bug.
Fixed SceneView expansion bug.

The correct Context wasn't being used to evaluate the children of the selection, meaning that if the viewed Nodes used any context variables or where time dependent, errors would occur.

Fixes #438.

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