Cursor visibility

Set default cursor visibility to false
- if a game has a script like Super Simple Mouse System of Shaz the cursor will become visible even if the mkxp.conf setting is set to false.

src/config.cpp

@@ -158,6 +158,7 @@ void Config::read(int argc, char *argv[])
 	PO_DESC(winResizable, bool, false) \
 	PO_DESC(fullscreen, bool, false) \
 	PO_DESC(fixedAspectRatio, bool, true) \
+	PO_DESC(showCursor, bool, false) \
 	PO_DESC(smoothScaling, bool, true) \
 	PO_DESC(vsync, bool, false) \
 	PO_DESC(defScreenW, int, 0) \