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.

include/decl.h

@@ -830,7 +830,7 @@ struct instance_globals_c {
     char *config_section_current;
     boolean chosen_symset_start;
     boolean chosen_symset_end;
- 
+
     /* invent.c */
     /* for perm_invent when operating on a partial inventory display, so that
        persistent one doesn't get shrunk during filtering for item selection
@@ -1603,6 +1603,9 @@ struct instance_globals_w {
     /* mkmaze.c */
     struct trap *wportal;
 
+    /* new */
+    struct win_settings wsettings;      /* wintype.h */
+
     boolean havestate;
     unsigned long magic; /* validate that structure layout is preserved */
 };