Dovecot core doesn't have copyright notices in header files.

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 allows extension of test commands that evaluate the message somehow.
Currently this is implemented only for the message header.
Extensions can thereby influence what headers are evaluated and how.

- Changed operand read functions to prove exec status return codes in stead of boolean.
- Restructured optional-operand, stringlist and string-match APIs to provide execution status (error code) upon failure.
- Corruption errors are only produced when the binary is actually corrupt. Normal failures should never cause a recompile attempt anymore.
- Simplified optional-operand API.
- Cleaned up test command implementations that use the string-match API.

Significantly improved handling of old/corrupt binaries and revised matching implementation in the process.

Introduced the concept of a sieve object to merge the coding of comparators, match types, address parts and other objects that might need to be represented in byte code (removes lots of code duplication).

Exported sieve-code-dumper from sieve-interpreter containing all code dumping related implementation. Now to remove all printfs....

Changed id_code for optional operands to signed and fixed a ext_my_id-related error in the vacation and copy extensions.

Moved address-part, match-type and comparator code registries from interpreter to binary where they belong.

Grouped runtime parameters into a single runtime environment and started implementation of result composition/execution.