Remove IWAD-specific definitions from edge_defs

[dashodanger]

This will prevent potential conflicts, i.e. trying to load a Doom 2 map from a PWAD when Doom 1 is the IWAD, etc. edge_defs should ideally be a very minimal core that a standalone game/pack would require to function

[LoboEire]

Actually this is a feature, not a bug.
In fact we went out of our way to make it happen IIRC, to allow loading Doom1, Doom2 and Sigil so you could choose from all 6 episodes in one boot.

[dashodanger]

Maybe as a good middle of the road solution, keep the defs aggregated but move copies of them to the Doom/Doom 2/Final Doom edge_base folders respectively so that we can still clear them out for the non-Doom games we support (and standalone titles)

[LoboEire]

Standalone games should be using #CLEARALL at the start of all their defs if it is capable of being truely standalone.

[dashodanger]

True, but DDFATK, DDFCOLM, DDFFONT, DDFIMAGE, DDFMOVIE, DDFSFX, DDFSTYLE, and DDFTHING are programmed to ignore the CLEARALL directive. Additionally, there are Doom-specific graphics/sounds/etc in edge_defs that wouldn't be needed for non-Doom games