* limit the total number of registrations per account
* when an account is unregistered, unregister all its channels

Previously, we generated and prepended a long salt before generating
password hashes. This resulted in the hash verification cutting off long
before it should do. This form of salting is also not necessary with
bcrypt as it's provided by the password hashing and verification
functions themselves, so totally rip it out.

This commit also adds the functionality for the server to automagically
upgrade users to use the new hashing system, which means better
security and more assurance that people can't bruteforce passwords.

No need to apply a database upgrade to do this, whoo! \o/

* Clients are now renamed, not disconnected, on reservation timeout
* Nick reservation config is now its own subsection

As well, add channel registration and re-applying founder privs on the first client joining the channel. I'm going to re-architect our modes system to better acocunt for this sort of change.

Avoids letting clients login to two accounts at once