Added immediate execution mode to OpDialogue.
Added immediate execution mode to OpDialogue.

This causes the dialogue to start with the op already executing, skipping the parameter editing phase.

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