Add Windows application manifest

- Use common controls 6 so error dialogs use correct visuals on
Windows XP or later!
- Specify running as invoker so Windows doesn't guess if it should
prompt for admin permission on Vista or later.
- Specify compatible with Vista through Windows 10. Tells Windows
not to emulate Vista behavior, not sure if it affects anything.

Makefile automatically runs windres when manifest changes.

code/sys/win_resource.rc

@@ -70,6 +70,12 @@ BEGIN
     IDS_STRING1             "Quake3"
 END
 
+/////////////////////////////////////////////////////////////////////////////
+//
+// Application Manifest
+//
+CREATEPROCESS_MANIFEST_RESOURCE_ID RT_MANIFEST "win_manifest.xml"
+
 #endif    // English (U.S.) resources
 /////////////////////////////////////////////////////////////////////////////