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.

src/options.c

@@ -106,11 +106,7 @@ static struct Bool_Opt {
 #endif
     { "clicklook", &iflags.clicklook, FALSE, SET_IN_GAME },
     { "cmdassist", &iflags.cmdassist, TRUE, SET_IN_GAME },
-#if defined(MICRO) || defined(WIN32) || defined(CURSES_GRAPHICS)
-    { "color", &iflags.wc_color, TRUE, SET_IN_GAME }, /*WC*/
-#else /* systems that support multiple terminals, many monochrome */
-    { "color", &iflags.wc_color, FALSE, SET_IN_GAME }, /*WC*/
-#endif
+    { "color", &iflags.wc_color, TRUE, SET_IN_GAME }, /* on/off: use WC or not */
     { "confirm", &flags.confirm, TRUE, SET_IN_GAME },
     { "dark_room", &flags.dark_room, TRUE, SET_IN_GAME },
     { "eight_bit_tty", &iflags.wc_eight_bit_input, FALSE, SET_IN_GAME }, /*WC*/