SRTM data is split into different directories, get a list of all of
            them and create a dictionary for easy lookup.

def createFileList(self):
        """SRTM data is split into different directories, get a list of all of
            them and create a dictionary for easy lookup."""
        global childFileListDownload
        if childFileListDownload is None or not childFileListDownload.is_alive():
            childFileListDownload = multiprocessing.Process(target=self.createFileListHTTP)
            childFileListDownload.start()