In http_get_line() additionally strip any trailing space or tab from lines.

In http_get_line() additionally strip any trailing space or tab from lines.
In many places the HTTP allows for extra spaces which need to be ignored.
Similar the chunked encoding extensions are separated from the chunk size
by a ':' but the spec also allows for bad whitespaces in all shapes and
forms. Adjust the logic in http_parse_chunked() to stop when the first
space, tab or ':' is seen. There is no need to check for newlines since
those are stripped by http_get_line().
OK tb@