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

Testsuite: tested handling of teststuite envelope environment and fixed bugs in the envelope test 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).

Added the concept of persistent tags and implemented imapflags extension for bare keep and fileinto commands (intermittent commit, not working properly yet).

Properly implemented dumping a binary including a list of required extensions and support for extension-specific output.

RECOVERED FROM INCONSISTENCY: developed testsuite and binary dumping and fixed various small issues.

Implemented support for overriding default argument implementations of number, string and string-list.

Properly implemented the code dumper. Dumps are now printed in a stream. The individual opcode and operand implementations no longer use printf()s.