For now this just highlights the current nickname, but it can cope
with a list of other patterns once we decide how to store and model
them.

Also for now, sets the BG colour to red. Need to make that
configurable.

Issue #36

Need this to figure out where to display them, for now.

Stab bits of ignored tests that no longer work.

This adds a sendLine method to Connection, which is a bit icky,
but is useful when the end-user is supplying lines to pass
directly to the underlying connection.

This introduces a CachingDocument which wraps around an IRCDocument
and allows UI-specific caching of UI-specific styled lines (so, e.g.
the web UI could cache HTML versions if it wanted).

Also adds a delegating message maker and attributed string maker,
which incorporates the old "make a StyledDoc then change it into
an AttributedString" logic found in ui.core.util.Utils.

Hopefully this should mean all the the swing stuff can be punted
into the swing UI. The delegated maker will also allow colouring
of the new events to be done sensibly, I think.

Put it behind a nice interface, so the styliser can work without it
and be tested, and other UIs don't have to use swing junk.

This is required by the plugins change.

Issue #213