cc_frm_button: add methode clearButtonDirectKeys()

Origin commit data
------------------
Commit: 7c683415f7
Author: Thilo Graf <dbt@novatux.de>
Date: 2020-12-07 (Mon, 07 Dec 2020)

src/gui/components/cc_frm_button.h

@@ -228,6 +228,12 @@ class CComponentsButton : public CComponentsFrmChain, public CCTextScreen
 			return RC_NOKEY;
 		}
 
+		/**
+		 * Remove all defined direct keys.
+		 * @return	void
+		 */
+		void clearButtonDirectKeys(){cc_directKeys.clear();}
+
 		/**
 		 * Returns count of existant direct keys of cc_directKeys container.
 		 * @return	size_t