Began bringing the client into line with the server's changes

Several parts of the client already built correctly.

Updated LobbyMenu, it not builds.
in_world.cpp is building
in_combat.cpp builds; entire repo builds

Doesn't mean I'm done yet.
Merge branch 'client-fix' into develop (read more)

The entire repository builds cleanly, but the client is still broken and
incompatible with the server. Still, I'm merging this build into develop.

I don't know if the client runs correctly.

Much of the modifications since branching from master are untested.