Tidied accounts_load in accounts
Renamed account_add_login -> account_add, added comments
Refactor fixing old accounts
Refactored connecting, and reconnecting

The user either logs in with an account, in which case its name, and the
password is kept for reconnects. Or the user can login with a jid (and
server) which does not currently exist as a local account.  On success
an account is created, with the jid as the name.