Hosting a file is now threaded.  Unfortunately, in doing so I broke downloading.  Will fix ASAP.
Client now continues downloading as long as files are being hosted (which is forever, since there is no way to stop hosting at the moment).
Now spawns a new thread to host the file that you just downloaded.
Started fixing things that required workarounds when we didn't have threads.
Fixed the client not checking for a <GET invalid> from peer.
Fixed server crashing on client disconnect.