CInfoViewer: add member killInfobarText()

Ensure that no unnecessary instance of Components infobox is generated
and paint only changed text.

src/gui/infoviewer.h

@@ -128,8 +128,11 @@ class CInfoViewer
 	void showRadiotext();
 	void killRadiotext();
 
+	//small infobox, shows a small textbox with a short message text,
+	//text must be located in a file named /tmp/infobar.txt
 	CComponentsInfoBox *infobar_txt;
 	void showInfoFile();
+	void killInfobarText();
 
 	//void loop(int fadeValue, bool show_dot ,bool fadeIn);
 	void loop(bool show_dot);