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
        global filelistDownloadActive
        mypid = os.getpid()
        if mypid not in childFileListDownload or not childFileListDownload[mypid].is_alive():
            childFileListDownload[mypid] = multiproc.Process(target=self.createFileListHTTP)
            filelistDownloadActive = 1
            childFileListDownload[mypid].start()
            filelistDownloadActive = 0
SRTM data is split into different directories, get a list of all of
            them and create a dictionary for easy lookup.