If special characters were included the source code (HTML-like ones like < and >) is was not rendered.
Fixes https://github.com/PrivateBin/PrivateBin/issues/588
It includes a change in the RegEx for URLs because that was broken when a
& character later followed at any time after a link (even after a newline).
(with a negative lookahead)
Test with https://regex101.com/r/i7bZ73/1
Now the RegEx does not check for _all_ chars after a link, but just for the
one following the link.
(So the lookahead is not * anymore. I guess thsi behaviour was
the expectation when it has been implemented.)
005d223c0d