* Fixes NB#59138, message is saved to drafts when main window is closed

	* Fixes NB#59138, message is saved to drafts when main window is closed
	* modest_msg_edit_window_is_modified is now public
	* modest_window_mgr.c: added a hash table to store the "window-destroy" signal handlers
	* modest_window_mgr.c: replaced a g_object_unref by gtk_widget_destroy
	* moved the save_to_drafts call from the edit window to the window manager
	* added some missing unrefs to the UI actions
	* fixed save_to_drafts mail operation, it was not reporting the mail operation status

pmo-trunk-r2397