Adds removing extra components and deleting entities clientside when
going back to the character screen. Also, simplifies ClientState by
removing the Dead variant and removing ClientMsg::StateRequest in favor
of more specific ClientMsg variants.
fix(overflow): Stops including block updates that fail (since chunks
don't exist on the client) in `TerrainUpdates` (which would trigger
meshing of those nonexistent chunks). Furthermore, removes
remeshing of chunks with block updates if those chunks don't have all their
neighbours (since those wouldn't be meshed in the first place).
