Utility functions common to fixture definitions.
A fixture definition where a single channel turns on or off the power at a socket to which an incandescent light source or other non-DMX-enabled equipment can be connected. If you are using a product such as the Chauvet DMX-4, its channels can be patched as four of these, or four generic-dimmer, or some combination.
Associates color wheel hue maps with the fixture and all its heads, for easy lookup when assigning color at the end of a color effect chain.
Associates function maps with the fixture and all its heads, for easy lookup by function-oriented effects.
Strips a mapped fixture (or fixture list) of keys which make it a pain to print, such as the back links from the heads to the entire fixture, and the function maps.
Returns all the fixtures or heads which might appear in the visualizer. If the fixture or head has an explicit :visualizer-visible boolean, that is honored, otherwise it is assumed that fixtures without heads are themselves relevant, while for fixtures with heads, only the heads are relevant.