Neutrino menu forwarder: add possibility to show value from jump target

based on idea by martii <m4rtii@gmx.de> in Neutrino-MP Git

src/gui/widget/menue.h

@@ -79,6 +79,7 @@ class CMenuTarget
 		virtual void hide(){}
 		virtual int exec(CMenuTarget* parent, const std::string & actionKey) = 0;
 		virtual fb_pixel_t getColor(void) { return 0; }
+		virtual const char * getTargetValue() { return NULL; }
 };
 
 class CMenuItem