Fixes issue for GNU/Hurd.

Modified patch by Andriy Syrovenko.

Patch by Timo Sirainen.

This change is bigger than I would have liked, so this needs to be tested more.

Emerged when Sieve and ManageSieve were merged into Pigeonhole.

The output from the script service was never read, causing a broken pipe error at the script service.
Apparently, this was broken since the I/O handling for extprograms was last revised.

Added --disable-shared to DISTCHECK_CONFIGURE_FLAGS (in dovecot.m4) to prevent libtool from relinking the libraries.

Sieve storage now updates sieve attributes in the user's INBOX if used by ManageSieve.

Patch by Timo Sirainen.

Forgot to rewind mail stream before header parsing.
Wrapped mail stream is obtained long before parsing, so if it is used in the mean time, it must be rewound to the beginning.

Patch by Timo Sirainen.

Still does not fix the ping-pong issue.

Change is preliminary. Still doing some experiments, 'ping-pong' problem is not solved.

Added flag to prevent warnings about non-link active scripts and disable critical error logging.
A rather fundamental synchronization problem remains to be solved.

Testsuite hostname is now true local hostname.

Patch by Timo Sirainen.

Some environment items in the base specification are not (yet) applicable to Dovecot and are therefore not supported.

Patch by Timo Sirainen.

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