Display a system icon for a custom actions

Refactored Icon cache
Refactored custom command spawning


FossilOrigin-Name: 2dabf7d89cfa79d1ce278c7b083761be5f54a691

src/MainWindow.h

@@ -62,6 +62,7 @@ private:
 	void setBusy(bool busy);
 	virtual QMenu *createPopupMenu();
 	const QIcon& getInternalIcon(const char *name);
+	const QIcon& getInternalFileIcon(const QFileInfo &finfo);
 
 	enum ViewMode
 	{