Added scrolling message output to OpDialogue.
Added scrolling message output to OpDialogue.

Fixes #591.

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