IMPORTANT: displacement and accelerative UDMF scrollers update

[printz]

When comparing Eternity and UDMF maps, I've discovered a long-standing mistake in the Eternity implementation of the Scroll_Floor, Scroll_Ceiling and Scroll_Texture_Model. The second arg's bits for choosing between displacement and accelerative scrolling were swapped wrongly in Eternity! This caused confusion for users and incompatibility between ports (when trying UDMF with ee_compat = true) and it was completely unintentional! So I've fixed the bits now to conform to the ZDoom definition. Apparently the Eternity documentation also followed the wrong rule, so I'll fix it too.

 

I've verified all wads from https://eternity.youfailit.net/wiki/List_of_maps_and_mods_made_for_Eternity that they use the displacement/accelerative specials neither on UDMF nor on ExtraData.

 

But if you have Eternity works in progress, please revise all your uses of Scroll_Floor, Scroll_Ceiling and Scroll_Texture_Model to use the correct accelerative/displacement bits. Sorry for this.