Editor: Replace emitter check boxes in Light records with "Emitter Type" combo box
We currently use four check boxes to determine the emitter type of a light source: "Flickering", "Slow Flickering", "Pulsing", and "Slow Pulsing" (implicit: ""). However, a light source may only have one emitter type. This feature should merge all the check boxes into an "Emitter Type" combo box in order to improve UI clarity as well as to prevent anyone from erroneously assigning two or more emitter types in the future.
(RM-3752 from redmine: created on 2017-02-16 by Martin Otto, , closed on 2017-02-17 by Martin Otto)