lib-sieve: storage: file: sieve-file-script - Only compare scripts using stat info when scripts are open

Finish the conversion to dict_init_auto() later.

If the mail store commit failed, the mail was not guaranteed to be saved.
We don't want to lose mails, even if e.g. a forward had just succeeded.

In that case, the header name and middle are empty, causing:

Panic: file edit-mail.c: line 820 (edit_mail_headers_parse): assertion failed: (body_offset > 0)

Fixed by skipping the bad header for parsing altogether.

This avoids adding another Message-id if one is already present but
of bad quality.

To prevent a maybe-uninitialized warning the autodetecting now sets the
storage_path parameter in any case.

These were originally written while the plugin was in draft. These can
be now removed as the RFC has been finalized and the commands were
dropped.

lib-sieve: sieve-storage, sieve-file-storage - Drop deprecated handling of 'sieve_dir' configuration

lib-sieve: plugins: include: ext-include-binary - Properly check whether binary dependency block load succeeded.

Otherwise, a segfault may occur on a corrupt binary.

The sieve_binary_block_index/get() functions return NULL when the block index is
invalid somehow. This was not handled by the dumper, thereby causing a crash.

Problem reported by scan-build.

lib-sieve: plugins: imap4flags: test-hasflag - Fix segfault occurring for command without arguments.

This is a corner case that doesn't happen in practice, but it can be created in
the test suite.

This reverts commit ffbcd3bf.

This applies to the vacation and notify actions, which produce new free-form
outgoing messages.