Fixes and more tests
- Add tests for Part.set
- Fix Part.set bugs turned up by tests
- Make Part.set install default values when applying patch where no object was previously present
- Implement ownKeys and getOwnPropertyDescriptor for managed list proxies (used by for...in loops)
- Add functional tests for ClusterServerBacking, only partially complete ATM
- Fix bugs in fabric-scoping turned up by previous
