display version and build info at startup (trunk only)

Tested on the unix port; I've updated as many other ports as I can figure
out but they're not tested.  See window.doc for info on the changed banner
lines.  Also adds the ability to override the generic "Unix" port - used now to get
"MacOSX" into the version line instead of "Unix" (so we don't scare people who don't
know what's going on).

win/X11/winX.c

@@ -55,6 +55,7 @@
 #else
 #include "patchlevel.h"
 #endif
+#include "date.h"
 
 #ifndef NO_SIGNAL
 #include <signal.h>
@@ -995,6 +996,7 @@ char** argv;
 	COPYRIGHT_BANNER_A,
 	COPYRIGHT_BANNER_B,
 	COPYRIGHT_BANNER_C,
+	COPYRIGHT_BANNER_D,
 	"",
 	"",
 	0