[svn] Commit various HTTP fixes.

[svn] Commit various HTTP fixes.
Published in <sxsy9slhu7g.fsf@florida.arsdigita.de>.

* http.c (gethttp): Return RETRUNNEEDED when the retrieval is
unneeded because the file is already there and fully downloaded,
and -c is specified.
(http_loop): Handle RETRUNNEEDED.

* wget.h (uerr_t): New value RETRUNNEEDED.

* http.c (http_loop): Set no_truncate for files that both exist
and are non-empty.
(gethttp): Consider the download finished when restval >= contlen,
not only when restval==contlen.
(gethttp): Handle redirection before giving up due to -c.
(gethttp): Clarify error message which explains that -c will not
truncate the file.
(gethttp): When returning CONTNOTSUPPORTED, don't forget to free
the stuff that needs freeing and release the socket.

* main.c (print_help): Wget booleans accept "off", not "no".