Prepared client.
Implemented server for existentialist's nightmare.

It's really primitive, but it runs.
Currently, there's no client for it.
And it has a ton of commented-out code and TODOs and FIXMEs and such.
Misc cleanup; added client_connection.

Removed a ton of crap from existentialist_server.erl.
Also added client_connection.erl, which is a necessary file that I
forgot to add in the previous commit. Sorry about that.
Server now sends information about all map cells.

Wow, list comprehensions are spiffy!