textures: include almost all textures in all IWADs

We have been operating since the beginning with the idea of only
including matching compatible textures for Phase 1 and 2 based on the
textures that appeared in Doom 1 and 2, including keeping some
exclusive to each game.

This is artifically limiting to map creators and there is no good
reason to keep it this way.  Fixes #588

lumps/textures/textures.cfg

@@ -37,10 +37,6 @@
 AASHITTY        64      64
 *   BODIES      0       0
 
-#ifdef DOOM1
-
-; these textures are in doom 1, but not doom 2
-
 ; aastinky is different to the original, it is 32 wide
 ; instead of 24. textures are supposed to have widths
 ; in powers of 2
@@ -267,13 +263,6 @@ TEKWALL3        128     112
 TEKWALL5        128     128
 *   WALL24_1    -120    -8
 
-; end of doom 1 textures
-
-#endif
-
-#ifdef DOOM2
-
-
 ; tnt texture support
 ; may conflict, not yet added - SW1GSTON		512	128
 ; may conflict, not yet added - SW2GSTON                512     128
@@ -1337,10 +1326,6 @@ ZZZFACE8        256     128
 ZZZFACE9        256     128
 *   RWDMON10    0       0
 
-; end of doom2-specific textures list
-
-#endif
-
 ; These textures are in both Doom 1 and Doom 2, but the texture
 ; definitions do not match between the two.
 
@@ -1841,15 +1826,9 @@ WFALL3          64      128
 WFALL4          64      128
 *   WFALL4      0       0
 
-#ifdef ULTDOOM
-
-; These textures are only in Ultimate Doom
-
 SKY4            256     128
 *   SKY4        0       0
 
-#endif
-
 ; Common textures (in all IWADs):
 
 ASHWALL2        64      128