Clear the TTS cache, removing all cache files from disk.

        .. versionadded:: 1.6.0

def clear_cache(self):
        """
        Clear the TTS cache, removing all cache files from disk.

        .. versionadded:: 1.6.0
        """
        if self.use_cache:
            self.log(u"Requested to clear TTS cache")
            self.cache.clear()