Some users may want to explicitly update the DNS serial number. Instead
of forcing them to update on each write, a new configuration option is
used so they can chose turn it off.
Even if this plugin is small, DNS zone editing may not be very frequent.
Therefore, there is no point defining those functions every time vim
start. Moving them to the autoload directory solve this problem.
These lines were added automatically and are not needed. They are not in
the boilerplate notice given in the Apache license and therefore can be
safely removed.
Having exactly two digits is very common but also restrictive. Hence, it
is now required to have at least one digit. However, the new serial will
be on at least two digits.
