It is still a plugin, but no longer a separate package.

Added support for the :optional tag of the include command.
Changed Sieve script API in the process; opening the script is now available as a separate step.

Incorporated sieve_duplicate plugin into main Pigeonhole tree as a normal extension (vnd.dovecot.duplicate).
Also restructured doc dir a bit in the process.

Made vnd.dovecot.debug extension available to the LDA plugin instead of only the command line tools.

Spamtest and virustest extensions: discarded whitespace at beginning of regexp and added syntax testsuite tests.

Fixed small bug in the i;ascii-numeric comparator and added extensive relational tests to the testsuite.