Make the IconManager injectable using a global config.

I'm planning on removing scoped IconManagers - it's a lot of effort
to maintain them and pass them in everywhere (instead of injecting
them) for almost no gain. I don't think we've ever set a per-server
or per-channel icon, and I can't imagine why we'd want to.

Remove PluginMetaData.getManager().

This is horribly icky and wrong. The only place it's used is
PluginFilesHelper, which can easily be given its own manager.

Also fix annoying shaded import.

Add a separate ServiceManager implementation.

Add test for HighlightManager, fix issues.

Alternative highlights were never added because the maps were
optimised away; then the list occasionally ended up with null
entries as they were added concurrently.

Bump autovalue.

Add core error dialog.

Split up client build file.

Makes it a bit less messy, and easier to find the right bits.

Remove defunct getCredentials method from build script.

Use correct assert methods.

Add a CommandErrorEvent and format.

Remove unused methods.

Remove MessageTarget.

For some reason it reordered the ctor parameters, so fix them too...

Remove references to MessageTarget.

Doesn't make sense to have this any more, as Chat provides the
common interface between queries + channels.

Move invite handling into a separate class.

Use new InviteManager iface.

Delete the duplicated methods from Connection.

Add an interface for an InviteManager.

Some more work on errors.

 - Add a ProgramErrorFactory
 - Add a ProgramErrorErrorManager (I'm awful at names...)

Remove Server.parseHostMask

Make GroupChatManager listen for channel closing.

Nicer than having Channel poke it explicitly.

Make ErrorManager nullable in ProgramError.