birdnotes.py: Objects to represent bird note files

This method constructs a Gps instance from its XML representation.

# - - -   G p s . r e a d N o d e

    @staticmethod
    def readNode(node):
        """Convert from XML
        """
        waypoint = node.attrib[rnc.WAYPOINT_A]
        text = node.text
        return  Gps(waypoint, text)