Remove some more ClientInfo usages.

Use User in Invite.

Use User in Topic.

Push some event handling into ServerEventHandler.

Initial work on highlight manager.

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

Tidy getUser methods in Server.

Fix unit test.

More work on events.

Make events use User.

Add a source to displayable events.

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

Colour events.

Switch events to USer.

Remove moved classes.

Stab bits of ignored tests that no longer work.

Really minor tidying.

Use forEach where possible.

Add a UserFactory and an implementation.

Remove more usages of Server.

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.

Add User + GroupChatUser objects.

Remove some more Server useages.

Change to Connection in ExternalCommands.