Clarify that definitions in Slots would be used in graceful enhancement for Color Attribute

[petrvanekrobe]

If Wheel → Slot defines Color, Gobo image, Filter and Prism (makes no sense), we should define what is used.

For example it is common to have multicolor color slot, so Gobo image (name "gobo image" is misleading here) should be used rather then Color.

https://gdtf-share.com/forum/index.php?/topic/373-help-with-an-xml-conversion%C2%A0/&do=findComment&comment=956

[petrvanekrobe]

#270