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.

win/tty/wintty.c

@@ -97,6 +97,11 @@ struct window_procs tty_procs = {
      | WC2_RESET_STATUS
 #endif
      | WC2_DARKGRAY | WC2_SUPPRESS_HIST | WC2_STATUSLINES),
+#ifdef TEXTCOLOR
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},   /* color availability */
+#else
+    {1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1},
+#endif
     tty_init_nhwindows, tty_player_selection, tty_askname, tty_get_nh_event,
     tty_exit_nhwindows, tty_suspend_nhwindows, tty_resume_nhwindows,
     tty_create_nhwindow, tty_clear_nhwindow, tty_display_nhwindow,