add glyphs+tiles for door+chest traps

When trap detection finds trapped doors and trapped chests, it shows
those as bear traps.  When the hero comes within view, they revert to
normal and the detected trap is forgotten.  This doesn't change that,
it is just groundwork to be able to show them distinctly.  Like the
TT_BEARTRAP patch, it increments EDITLEVEL so this seemed like a good
time to put the groudwork in place.

There shouldn't be any visible changes even though internal glyph and
tile values have been renumbered after inserting two new entries.
Adding traps after S_vibrating_square was quite a hassle and suffered
though a couple of off-by-one errors that weren't trivial to find and
fix.

include/trap.h

@@ -77,9 +77,18 @@ enum trap_types {
     MAGIC_TRAP   = 20,
     ANTI_MAGIC   = 21,
     POLY_TRAP    = 22,
-    VIBRATING_SQUARE = 23,
+    VIBRATING_SQUARE = 23, /* not a trap but shown/remembered as if one
+                            * once it has been discovered */
 
-    TRAPNUM      = 24
+    /* trapped door and trapped chest aren't traps on the map, but they
+       might be shown/remembered as such after trap detection until hero
+       comes in view of them and sees the feature or object;
+       key-using or door-busting monsters who survive a door trap learn
+       to avoid other such doors [not implemented] */
+    TRAPPED_DOOR = 24, /* part of door; not present on map as a trap */
+    TRAPPED_CHEST = 25, /* part of object; not on map */
+
+    TRAPNUM = 26
 };
 
 /* some trap-related function return results */