Update channel/nick/query tooltips to new-style

Update channel/nick/query tooltips to new-style

Modify channel, network, query and nick tooltips to use a clean,
consistent style with more padding, trading efficiency for
readability. This significantly helps for tooltips with lots of
information.

Unify HTML escaping, reducing some clutter of '#if QT_VERSION'.

Fix crashes and weird formatting by escaping HTML where reasonable,
such as nick ident information.  In titles, spaces are replaced with
non-breaking spaces to avoid line-wrapping.

Expands upon a2e0951abbe2d545836fb25fd6010aa085f17d82
Thanks to https://github.com/Scheirle for the first version!