Continuing my recent streak of making random lighting/colormap-related fixes to long-standing bugs:

* Fix that thing where ALL transparent FOF planes were continuously fullbright unless encased in a fog which disables sprite fullbrightness, which was long-hated by many people in the community!
	* For backwards compatibility, setting flag 1 in that fog field (which is probably the most common "in-the-wild" usage of this feature) will continue to make objects un-fullbright.
	* For situations where you desperately want the behaviour to be enabled, you can apply fog flag 2.
* Change the fadestart and fadeend range in which colormaps are generated.
	* The problem HERE was that the darkest light level reached by generated colormaps was actually slightly brighter than the darkest level reached by normal colormaps.
	* The typo I fixed does have SOME basis in fact - standard colormap lumps are 34 (33 in 0-indexing) long rather than 32 (31), but whoever wrote this didn't realise that the code for generating them didn't do it DooM style, just bright-to-dark with no extras on the end...