Message 182321 - Python tracker

Updated version of the patch.

Changed from review:
- Included test.bytecode_helper module used by some tests
- Updated docs to indicate that the changes are new in 3.4
- ByteCode -> Bytecode
- Added meaningful repr for Bytecode

Still to do:
- ? Re-expose attributes from code object on Bytecode instance
- Tests & documentation for Bytecode class
- Split changes into multiple patches