Mimics Dovecot/IMAP change 1001bda65e9f592d852a26ddd6a993f7973050bf.

This allows completely disabling Sieve processing for a particular user.

Changed handling of ENOSPACE to a normal temporary failure and added handling of ENOQUOTA as a user error.
Patch by Timo Sirainen.

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

Most important change is that mail service_user was not freed.

Parallel to identical Dovecot change for imap and pop3.

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

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

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

  - 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.

This change matches a similar change in Dovecot for IMAP/POP3.
Also includes other small changes that make ManageSieve match IMAP implementation a little more closely.

ManageSieve: added support for reading quoted and literal strings as a stream. Fixes support for handing large SASL responses.
Also resolves long-standing FIXME regarding the second parameter of PUTSCRIPT: it can now be a quoted string.
Includes a few small changes in the login daemon that were done in the dovecot equivalents before.

Enforced ManageSieve protocol syntax better with some of the commands; some commands still allowed spurious extra arguments.

- 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.