CFrameBuffer: fb-generic.cpp - add methode for clean up icon cache

This could be required eg. on changed resoulutions or
changed iconsets on runtime.


Origin commit data
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Commit: 4e66739ff5
Author: Thilo Graf <dbt@novatux.de>
Date: 2017-08-02 (Wed, 02 Aug 2017)

src/driver/fb_generic.h

@@ -239,6 +239,7 @@ class CFrameBuffer : public sigc::trackable
 				const int h = 0, const unsigned char offset = 1, bool paint = true, bool paintBg = false, const fb_pixel_t colBg = 0);
 		bool paintIcon8(const std::string & filename, const int x, const int y, const unsigned char offset = 0);
 		void loadPal   (const std::string & filename, const unsigned char offset = 0, const unsigned char endidx = 255);
+		void clearIconCache();
 
 		bool loadPicture2Mem        (const std::string & filename, fb_pixel_t * const memp);
 		bool loadPicture2FrameBuffer(const std::string & filename);