has_color() performance fixes

Performance profiling showed that multiple strcmpi() calls were
occurring each and every time a character was going to the map.

This update:
- honors the WC_COLOR capability
- It allows a window-port to control individual color availability should the window-port wish to do so.
- Makes checking on the individual colors for the active window-port is a straightforward table lookup at the CLR_ offset.

iflags.use_color remains a master on/off switch for use of color, regardless of the capability
compiled into the game (default TRUE).

The has_color() routine, which is now a shared routine in src/windows.c, could likely be made
into a simple macro to eliminate the function call, but this update does not go that far.

This hits a lot of port files due to the window-port interface change, mostly cookie-cutter.

include/winprocs.h

@@ -14,6 +14,7 @@ struct window_procs {
                            * '+' are reserved for processors. */
     unsigned long wincap; /* window port capability options supported */
     unsigned long wincap2; /* additional window port capability options */
+    boolean has_color[CLR_MAX];
     void FDECL((*win_init_nhwindows), (int *, char **));
     void NDECL((*win_player_selection));
     void NDECL((*win_askname));