[svn] Various url.c-related changes.

[svn] Various url.c-related changes.
Published in <sxsvgo8nmub.fsf@florida.arsdigita.de>.

* retr.c (retrieve_url): Call uri_merge, not url_concat.
* html-url.c (collect_tags_mapper): Call uri_merge, not
url_concat.
* url.c (mkstruct): Use encode_string instead of xstrdup followed
by URL_CLEANSE.
(path_simplify_with_kludge): Deleted.
(contains_unsafe): Deleted.
(construct): Renamed to uri_merge_1.
(url_concat): Renamed to uri_merge.
* url.c (str_url): Use encode_string instead of the unnecessary
CLEANDUP.
(encode_string_maybe): New function, returns input string if no
encoding is needed.
(encode_string): Call encode_string_maybe to do the dirty work,
xstrdup if no work needed.
* wget.h (XDIGIT_TO_xchar): Define here.
* url.c (decode_string): Use new name.
(encode_string): Ditto.
* http.c (XDIGIT_TO_xchar): Rename HEXD2asc to XDIGIT_TO_xchar.
(dump_hash): Use new name.
* wget.h: Rename ASC2HEXD and HEXD2ASC to XCHAR_TO_XDIGIT and
XDIGIT_TO_XCHAR respectively.