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/cursdial.h

@@ -15,7 +15,7 @@ int curses_ext_cmd(void);
 void curses_create_nhmenu(winid wid, unsigned long);
 void curses_add_nhmenu_item(winid wid, const glyph_info *glyphinfo,
                             const ANY_P *identifier, char accelerator,
-                            char group_accel, int attr,
+                            char group_accel, int attr, int clr,
                             const char *str, unsigned itemflags);
 void curs_menu_set_bottom_heavy(winid);
 void curses_finalize_nhmenu(winid wid, const char *prompt);