added EmptyTrash()

mailnews/base/public/nsIMessenger.idl

@@ -63,6 +63,7 @@ interface nsIMessenger : nsISupports {
     void RenameFolder(in nsIRDFCompositeDataSource db, 
                       in nsIDOMXULElement folder, in string name);
     void CompactFolder(in nsIRDFCompositeDataSource db, in nsIDOMXULElement folder);
+    void EmptyTrash(in nsIRDFCompositeDataSource db, in nsIDOMXULElement folder);
 
     void Undo();
     void Redo();

mailnews/base/public/nsIMsgFolder.idl

@@ -74,6 +74,7 @@ interface nsIMsgFolder : nsIFolder {
 	void CreateSubfolder(in string folderName);
 
   void Compact();
+  void EmptyTrash();
 
 	void Rename(in string name);
 	void Adopt(in nsIMsgFolder srcFolder, out unsigned long outPos);