Delete ClientWrapper before shutdown, which allows all of the async tasks in bts::client, bts::net, etc. to shutdown cleanly (fixes crashes & asserts at shutdown)
Updates to shutdown procedure. It still doesn't work right, but it's better.
Detonate implosion grenade as soon as client is destroyed.

Screw you, sleeping threads! I keel you! Hahahahaaaa!
Fix spurious crash detection
Revert exit call and cleanup shutdown of bitshares client so that GUI shuts down properly.
Avoid capturing a smart pointer to the wallet in a lambda owned by the wallet, which was preventing it from being garbage collected.
Remove some old fc logfile managing code inherited from keyhotee and no longer useful.