noteweb: Rendering bird field notes for the Web

This method returns the number of months in self. Note: if there is a year directory but there were no valid month files in it, this method will return zero.

# - - -   Y e a r R o w . _ _ l e n _ _

    def __len__ ( self ):
        '''Return the number of contained months.
        '''
        return len(self.__monthMap)