By Timo Sirainen.

Apparently automakes in future won't support configure.in anymore.

Forgot to skip line upon error.

Added means to log user errors/warnings as info in master log.
Previous change was inadequate because an error was still logged.

Prevents administrator frustration about useless log messages caused by users with too much mail.

lib-sieve: include extension: didn't get semantics of mixing optional and non-optional includes for the same script quite right.

Change backported from Pigeonhole v0.4 tree, which means that this change will duplicate there upon merge.

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.

This was broken by the ld.gold fix.

Those version numbers are now also stored in the binary, making sure it is recompiled
when a new version of an extension is used. This avoids updating the binary version
for minor changes to extensions and also makes this work for plugins.

sieve-refilter: improved man page documentation by explicitly specifying the syntax used for mailbox arguments.