CMsgBox: rework msgbox classes with Window class implementation

Replacing messagebox, hintbox_ext and some derivated parts with
basic class hintbox and derivated class CMsgBox. This should unify
window handling and avoids maintain of multiple classes with quasi
same purpose and adds more functionality.

TODO: fix and optimize details


Origin commit data
------------------
Commit: dde298b1b7
Author: Thilo Graf <dbt@novatux.de>
Date: 2016-04-04 (Mon, 04 Apr 2016)

src/gui/components/cc_frm_window.h

@@ -222,6 +222,11 @@ class CComponentsWindow : public CComponentsForm
 
 		///paint all window items, this overwriting paint() from CComponentsForm
 		void paint(bool do_save_bg = CC_SAVE_SCREEN_YES);
+
+		///adds additional exec key to current collection, default exit keys are CRCInput::RC_home and CRCInput::RC_setup
+		virtual void addExitKey(const neutrino_msg_t& key){getBodyObject()->addExitKey(key);}
+		///remove all current exec keys from current collection, NOTE: use addExitKey() if new exec key is required
+		virtual void removeExitKeys(){getBodyObject()->removeExitKeys();}
 };
 
 class CComponentsWindowMax : public CComponentsWindow