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.

sys/wince/mswproc.c

@@ -50,6 +50,7 @@ struct window_procs mswin_procs = {
         | WC_TILE_WIDTH | WC_TILE_HEIGHT | WC_TILE_FILE | WC_VARY_MSGCOUNT
         | WC_WINDOWCOLORS | WC_PLAYER_SELECTION,
     WC2_FULLSCREEN | WC2_SOFTKEYBOARD | WC2_WRAPTEXT, mswin_init_nhwindows,
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},   /* color availability */
     mswin_player_selection, mswin_askname, mswin_get_nh_event,
     mswin_exit_nhwindows, mswin_suspend_nhwindows, mswin_resume_nhwindows,
     mswin_create_nhwindow, mswin_clear_nhwindow, mswin_display_nhwindow,