Instead of passing them in to the FrameContainer ctor, create
them afterwards.

This means the reference in FrameContainer can't be final but
removes the horrible setOwner() kludge that was previously in
CommandParser, and cuts down the deps needed to pass in to the
FrameContainer ctor.

(This depends on a plugins change)

This just provided default implementations of most of the
ReadOnlyConfigProvider interface, which as of J8 we can
now just put in the interface itself.

This is a little bit icky, but I can't see a nicer way to do it.

From everywhere.

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.

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.

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

Delete the duplicated methods from Connection.

For now this is just a straight(ish) copy of the way Server worked.
Need to make it use events in the future which should simplify it
quite a bit.

Remove them from the Connection interface.

This isn't used in the UI, and doesn't need to exist with the
individual setter methods.