The inverse of decode_words_tokenized_labled() , this functions accepts
an array like the argument to quote_labled() , but "word" labled
elements can optionally contain an additional string element specifying
a character set, in which case an encoded-word will be used. Also, the
format for "comment" labled elements is entirely different; instead of
a single string, an array of strings or pairs like the first argument to
encode_words_text() is expected.
Parameter encoding
Either "base64" or "quoted-printable"
(or either "b" or "q" for short).