TTY: Hilight piles of objects

Add MG_OBJPILE flag, which windowports can use to check if a location
has more than one object stack. If use_inverse is on, TTY will use
inverse to show such piles.  If a boulder is the topmost item on a pile,
then the object pile flag is not used; mainly because boulders are "solid",
boulders dropped by monsters are nearly always over other objects, and so
that special levels such a Sokoban can "hide" items under the boulders.

TODO: a "pilemark", analogous to "petmark", perhaps a green plus sign,
which can be used by windowports with tiles.

include/hack.h

@@ -60,6 +60,7 @@
 #define MG_PET 0x08
 #define MG_RIDDEN 0x10
 #define MG_STATUE 0x20
+#define MG_OBJPILE 0x40  /* more than one stack of objects */
 
 /* sellobj_state() states */
 #define SELL_NORMAL (0)

src/mapglyph.c

@@ -83,6 +83,8 @@ unsigned *ospecial;
         else
             obj_color(STATUE);
         special |= MG_STATUE;
+	if (level.objects[x][y] && level.objects[x][y]->nexthere)
+	    special |= MG_OBJPILE;
     } else if ((offset = (glyph - GLYPH_WARNING_OFF))
                >= 0) { /* a warning flash */
         idx = offset + SYM_OFF_W;
@@ -149,6 +151,8 @@ unsigned *ospecial;
             }
         } else
             obj_color(offset);
+	if (offset != BOULDER && level.objects[x][y] && level.objects[x][y]->nexthere)
+	    special |= MG_OBJPILE;
     } else if ((offset = (glyph - GLYPH_RIDDEN_OFF)) >= 0) { /* mon ridden */
         idx = mons[offset].mlet + SYM_OFF_M;
         if (has_rogue_color)
@@ -166,6 +170,8 @@ unsigned *ospecial;
         else
             mon_color(offset);
         special |= MG_CORPSE;
+	if (level.objects[x][y] && level.objects[x][y]->nexthere)
+	    special |= MG_OBJPILE;
     } else if ((offset = (glyph - GLYPH_DETECT_OFF)) >= 0) { /* mon detect */
         idx = mons[offset].mlet + SYM_OFF_M;
         if (has_rogue_color)

win/tty/wintty.c

@@ -3040,7 +3040,7 @@ int glyph, bkglyph;
 
     /* must be after color check; term_end_color may turn off inverse too */
     if (((special & MG_PET) && iflags.hilite_pet)
-        || ((special & MG_DETECT) && iflags.use_inverse)) {
+        || ((special & (MG_DETECT|MG_OBJPILE)) && iflags.use_inverse)) {
         term_start_attr(ATR_INVERSE);
         reverse_on = TRUE;
     }