Adds a breakpoint for the given line number to this edit.
        
        :note       The lineno is 0-based, while the editor displays lines as
                    a 1-based system.  So, if you want to put a breakpoint at
                    visual line 3, you would pass in lineno as 2
        
        :param      lineno | <int>

def addBreakpoint( self, lineno = -1 ):
        """
        Adds a breakpoint for the given line number to this edit.
        
        :note       The lineno is 0-based, while the editor displays lines as
                    a 1-based system.  So, if you want to put a breakpoint at
                    visual line 3, you would pass in lineno as 2
        
        :param      lineno | <int>
        """
        if ( lineno == -1 ):
            lineno, colno = self.getCursorPosition()
            
        self.markerAdd(lineno, self._breakpointMarker)
        
        if ( not self.signalsBlocked() ):
            self.breakpointsChanged.emit()