Added graphics for better wall/chasm transitions.

Also use them for wall/lava for the time being.

data/terrain-graphics.cfg

@@ -801,7 +801,10 @@
 {DISABLE_TRANSITIONS Xu}
 {DISABLE_TRANSITIONS (Cud,Kud)}
 
-{TERRAIN_ADJACENT_CORNER_BOTH  Xu               (!,Xu,Cud,Kud,_K)                      cavewall}
+{TERRAIN_ADJACENT_CORNER_BOTH  Xu               (!,Xu,Cud,Kud,_K,Qxu,Ql)               cavewall}
+{TERRAIN_ADJACENT_CORNER       Xu               (!,Xu,Cud,Kud,_K,Qxu,Ql)  (Qxu,Ql)     54,68 cavewall-convex}
+{TERRAIN_ADJACENT_CORNER       Xu               (Qxu,Ql)    (!,Xu,Cud,Kud,_K,Qxu,Ql)   54,68 cavewall-convex}
+{TERRAIN_ADJACENT_CORNER_BOTH  Xu               (Qxu,Ql)                               cavewall-chasm}
 
 {TERRAIN_ADJACENT_CORNER_BOTH  (Cud,Kud)        (!,Xu,Qxu,Ql,Cud,Kud,_K)               castle/dwarven-castle}
 {KEEP_ADJACENT_CORNER_BOTH     Cud              (!,Xu,Qxu,Ql,Cud,_K)   keep-of-cud     castle/dwarven-castle}