InteractiveRenderUI : Tiny tweaks.
InteractiveRenderUI : Tiny tweaks.

- Remove hasLabel() override, since the default returns False anyway.
- Use contexts only to execute `getValue()`, reducing indentation of remaining code, and clarifying that it is not context sensitive.
- Use `elif` where appropriate.

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