Change menu_headings to accept color and attribute

Instead of just accepting an attribute, it's now possible to
use a color, or both color and attribute, for example:

OPTIONS=menu_headings:inverse
OPTIONS=menu_headings:red
OPTIONS=menu_headings:red&underline

Default is still just inverse.
This lets the player change the menu heading color without
needing to use menu colors for them.

Also makes it so the core uses NO_COLOR instead of 0, for all
the menu lines which don't have any prefedefined color.

Tested for tty, curses, x11, qt, and win32

win/curses/cursmain.c

@@ -682,7 +682,7 @@ void
 curses_add_menu(winid wid, const glyph_info *glyphinfo,
                 const ANY_P *identifier,
                 char accelerator, char group_accel, int attr,
-                int clr UNUSED, const char *str, unsigned itemflags)
+                int clr, const char *str, unsigned itemflags)
 {
     int curses_attr;
 
@@ -694,14 +694,14 @@ curses_add_menu(winid wid, const glyph_info *glyphinfo,
         /* persistent inventory window; nothing is selectable;
            omit glyphinfo because perm_invent is to the side of
            the map so usually cramped for horizontal space */
-        curs_add_invt(inv_update, accelerator, curses_attr, str);
+        curs_add_invt(inv_update, accelerator, curses_attr, clr, str);
         inv_update++;
         return;
     }
 
     curses_add_nhmenu_item(wid, glyphinfo, identifier,
                            accelerator, group_accel,
-                           curses_attr, str, itemflags);
+                           curses_attr, clr, str, itemflags);
 }
 
 /*