VMM: moved functions ace2idna(), check_domainname(), idn2ascii()
and relevant parts to the Domain module.
Adjusted imports in modules AliasDomain, EmailAddress and Handler.
Config
   cfs - configset sect.opt val
   cfg - configget sect.opt
   ds - domainservices: smtp pop imap sieve???
- Aliases
    - avoid looping aliases
- Domain
    - optional limits for number of:
        + accounts
        + aliases
        + destinations/alias
        + alias domains