handles one authority file including format auto-detection.

def _loadOneSource(self, sourceFName):
        """handles one authority file including format auto-detection.
        """
        sourceLines = open(sourceFName).readlines()
        del sourceLines[0]
        if len(sourceLines[0].split("\t"))==2:
            self._loadTwoPartSource(sourceFName, sourceLines)
        elif len(sourceLines[0].split("\t"))==3:
            self._loadThreePartSource(sourceFName, sourceLines)
        else:
            raise Error, "%s does not appear to be a source authority file"