Sieve filter limit MTA options

The MTA has configurable limits on how many of various Sieve actions can be applied in a Sieve filter, and on the size of certain Sieve constructs.

See also:
 * max_addheaders MTA Option
 * max_duplicates MTA Option
 * max_fileintos MTA Option
 * max_notifys MTA Option
 * max_redirect_addresses MTA Option
 * max_redirects MTA Option
 * max_sieve_list_size MTA Option
 * max_sieve_match_iterations MTA Option
 * max_sieve_string_size MTA Option
 * max_vacations MTA Option
 * max_variables MTA Option
 * MTA options
 * Sieve filter MTA options
 * Sieve language