Fix prefs category loading.

Fix header names in URLHandlers prefs dialog.

When loading a category, don't also create UI for the subcategories.
This is weird and doesn't make sense, and is also the reason we
needed the hacky NoRemovePanel.

Previously, we added a category, then created a new panel for
each of its subcategories. When you clicked on the subcat
we made it again with a new panel, and the component ended
up on both (because it couldn't be removed from the old one).

Add Edit support to GenericTableModel, use it for updates.

Replace MapList with Multimap.

Fix error popup disagreeing with error counts.

Remove URLHandlerTableModel.

Remove JXLayer, migrate to JLayer.

Remove backbuffer timestamp completely.

Add framework for channel who plugin.

Add raw support in debug plugin.

Closes #207

Fix copying styled text bug.

Trying to copy 0 chars from a line is silly and breaks things.

Stop using addline without timestamp.

Fix misnamed clients in logging plugin logging.

Remove use of ChannelInfo.

Changes to channel commands done in core.

Fix another couple of bugs in the profiles dialog.

Try to speed up CI a bit.

Stop trying to select a value past the end of the list.

Try without using gradle's parallel function (probably adds more
overhead for the tiny number of tests we have), and combine
coveralls with the main test run.

Also some minor tidying.

Bug fixes for the profiles dialog.