Changed TabbedContainer to allow cropping by SplitContainer.
Changed TabbedContainer to allow cropping by SplitContainer.

Previously it wouldn't resize any smaller than the minimum needed to display all tabs. This didn't interact well when trying to collapse a section or when the label for a tab increased in size spontaneously (for instance because it was displaying a node name).

Fixes #93.

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