Now imapsql module does not handle authentication. (it was not doing it so well
anyway)
sql_table module was introduced and used in the default configuration as
a replacement for functionality that was implemented by imapsql before.
Parts of maddyctl code were rewritten to make it work transparently with
any IMAP backend or credentials store.
Closes#212.
With new authorization/authentication identities split, it is possible
to have non-email authentication identity while using email authorization
identity.
