Made NodeGraph restore previous framing when changing root.
Made NodeGraph restore previous framing when changing root.

This makes popping in and out of Boxes a lot less confusing, because you now pop back to the same framing you had when you left.

Fixes #626.

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