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.

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

path-util is a merge of realpath from Pigeonhole and abspath from core.

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

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

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 (modified).

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

Before, sievec and sieve-dump would switch to mail_uid:mail_gid and then fail to compile/dump a root script.

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

Clang static analyzer is happy now.

  - Built generic interface for alternative script sources.
  - Implemented dict script location.
  NOTE: ManageSieve will not work with this yet, nor will sieve_before/sieve_after.

- Added sieve_global_extensions setting.

Configuration is now only read once at extension initialization.

- Administrators now get properly notified about uncompiled global scripts and the inability of the sieve plugin to store global binaries.
- Improved binary load/save error handling and fixed a few smal bugs.
- Simplified ManageSieve error handling.