introduce support for coloring the frame behind a map location

Also includes support by paxed for polearm targeting using the
frame color.

Also renames USE_TILES to TILES_IN_GLYPHMAP which is a more
accurate description.

Not all window interfaces have full support for the color framing
of the background square yet.

MS-DOS needs further work (to bring it to both VESA and VGA, with
and without tiles.

Windows GUI is missing support.

X11 and Qt have been started, but may require further refinement.

sys/msdos/msdos.c

@@ -58,7 +58,7 @@ unsigned long sys_random_seed(void);
 static char *getdta(void);
 #endif
 static unsigned int dos_ioctl(int, int, unsigned);
-#ifdef USE_TILES
+#ifdef TILES_IN_GLYPHMAP
 extern boolean pckeys(unsigned char, unsigned char); /* pckeys.c */
 #endif
 
@@ -281,7 +281,7 @@ BIOSgetch(void)
             else
                 ch = kpad[scan - KEYPADLO].normal;
         }
-#ifdef USE_TILES
+#ifdef TILES_IN_GLYPHMAP
         /* Check for special interface manipulation keys */
         if (pckeys(scan, shift)) {
             ch = 0xFF;