'Creates a new feature from filename'

@classmethod
def from_file(new_feature, filename):

    f = codecs.open(filename, 'r', 'utf-8')
    string = f.read()
    f.close()
    language = Language.guess_from_string(string)
    feature = new_feature.from_string(string, with_file=filename, language=language)
    return feature
