lib-sieve: Added sieve_script_env_init() to initialize struct sieve_script_env from struct mail_user.

Now using struct smtp_address rather than sieve_address.
In some cases, struct message_address may prove to be more suitable, but this is the best fit for now.
Adjusted to the renamed fields in struct mail_deliver_context.

The Dovecot API was changed years ago, but apparently sieve-filter was never updated.

Normally, this would merely be an inconsequential memory leak.
However, when the script comes from an LDAP storage, the storage is not closed before master_service_deinit() -> io_loop_destroy().
The LDAP connection's stale io can cause problems while closing the main ioloop.

This adds a new callback to the Sieve script execution environment.

Used the following script:

C_FILES=`git ls-files *.c`
H_FILES=`git ls-files *.h`
for F in "$C_FILES $H_FILES"; do
        echo "$F"
  perl -p -i -e 's/safe_memset\(&\(?([^,]*)\)?,\s*0,\s*sizeof\(\g1\)\)/i_zero_safe(&$1)/g' $F
  perl -p -i -e 's/safe_memset\(([^,]*),\s*0,\s*sizeof\(\*\g1\)\)/i_zero_safe($1)/g' $F
  perl -p -i -e 's/memset\(&\(?([^,]*)\)?,\s*0,\s*sizeof\(\g1\)\)/i_zero(&$1)/g' $F
  perl -p -i -e 's/memset\(([^,]*),\s*0,\s*sizeof\(\*\g1\)\)/i_zero($1)/g' $F
done

Found with clang -Wstrict-bool.

Found with clang -Wstrict-bool.

perl -i -pe 's/unsigned int ([^,:;]+):1;/bool $1:1;/' **/*.[ch]

In effect, this adds PIE and RELRO to binaries.

lib-sieve: Implemented support for writing runtime trace output to a directory if it exists, much like Dovecot rawlog.

lib-sieve: Renamed sieve_runtime_flags to sieve_execute_flags and made these available to result execution.

lib-sieve: Moved handling of implicit keep during multiscript execution outside the script sequence itself.
Before, implicit keep was executed as part of the final script execution. This caused the implicit keep to be executed as part of that script, including global context.
This caused insignificant errors during delivery to be logged as errors in the administrator log when the last script is global.

sieve-filter: Fixed handling of failure-related implicit keep when there is an explicit default destination folder.
The message was left in the source mailbox, even though it was stored in the destination folder.

LDA Sieve plugin: Changed error handling so that each action log message can have up-to-date time stamps.
This change matches a change in LDA that is aimed at logging timing statistics.

Doveadm-sieve plugin may be broken at this point; not tested so far.

SMTP API now supports adding multiple recipients to a single SMTP transaction. This makes enotify/notify more efficient, since only one message is actually sent.

Patch by Timo Sirainen.

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

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