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/amiga/winami.c

@@ -28,7 +28,9 @@ long amii_scrnmode;
  * the intuition interface for the amiga...
  */
 struct window_procs amii_procs = {
-    "amii", WC_COLOR | WC_HILITE_PET | WC_INVERSE, 0L, amii_init_nhwindows,
+    "amii", WC_COLOR | WC_HILITE_PET | WC_INVERSE,
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},   /* color availability */
+    0L, amii_init_nhwindows,
     amii_player_selection, amii_askname, amii_get_nh_event,
     amii_exit_nhwindows, amii_suspend_nhwindows, amii_resume_nhwindows,
     amii_create_nhwindow, amii_clear_nhwindow, amii_display_nhwindow,
@@ -60,7 +62,9 @@ struct window_procs amii_procs = {
  * a shared library to allow the executable to be smaller.
  */
 struct window_procs amiv_procs = {
-    "amitile", WC_COLOR | WC_HILITE_PET | WC_INVERSE, 0L, amii_init_nhwindows,
+    "amitile", WC_COLOR | WC_HILITE_PET | WC_INVERSE,
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1},   /* color availability */
+    0L, amii_init_nhwindows,
     amii_player_selection, amii_askname, amii_get_nh_event,
     amii_exit_nhwindows, amii_suspend_nhwindows, amii_resume_nhwindows,
     amii_create_nhwindow, amii_clear_nhwindow, amii_display_nhwindow,