[Util] Pass cache dir by const ref.
[Azoth CH] Handle MUC destroyed before logs are fetched.

Fixes #1357.
[Azoth BN] Code style fixes.
[Azoth Murm] Implement IMetaInfoEntry for VkEntry.

And return birth dates.
[Azoth OTRoid] Avoid segfaults on key generation.

Short-circuit message sending/receiving hooks so that (thread-unsafe)
libotr isn't bothered while it generates keys.
Merge branch 'master' of github.com:0xd34df00d/leechcraft