Testsuite failed with an assertion, because the stream returned -2 at an unexpected time.
I've restructured the buffering implementation to prevent this.
The testsuite succeeds now, but this needs to be tested more thoroughly.

Also contains a few other small fixes by Timo.

Also fixed a small mistake in the spefication for the vnd.dovecot.duplicate extension.

lib-sieve: increase action instance count (for limit checking) only when an action is actually created.

Added test for interaction between include extension and dict script location support.

Sieve script equality function implementation was wrong.

Patch by Eray Aslan.

Patch by Timo Sirainen.

This currently breaks uninstall when the settings plugins are removed and 20-managesieve.conf
remains in conf.d directory. These sections only need to be active in the config file when settings
for the services themselves need to be disabled.

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

Clang static analyzer is happy now.