* Fixed NB#62792, the editor is closed if the account is removed

    * Fixed NB#62792, the editor is closed if the account is removed
        * Added modest_signal_mgr_disconnect, for disconnecting a single handler
        * Added the signal parametter to modest_signal_mgr_connect, this way we can add multiple connections for the same object
        * Renamed modest_window_mgr_(set/get)_modal_dialog to modest_window_mgt_(set/get)_modal because we can set a normal window as modal as well
        * Implemented a queue of modal dialogs in the window mgr, this way if the top one is removed the second one becomes the topmost

pmo-trunk-r3441