Stabilized New Engine. Now we can do unhook!

Several hook engine updates and bug fixes.

For details, check CHANGES.md.

Probably The First Plausible Release

Add several remarkable feature:

  1. Protobuf base class hack
  2. dict update method
  3. dict indexing, setting and 'in' operator
  4. repeated field list assignment (though not very efficient)

See the project README for more details.