Object snapshots

[ermau]

Currently, object values are simply strings generated by [DebuggerDisplay] and/or .ToString(); We need to be able to take a snapshot of the object's state if we ever want to be able to move closer to debugger-like functionality.

We could:

1. Create a deep copy of the object (hard, slow, complete)
2. Track external property changes differently, associating it with the object (easy, faster, far from complete)

This would probably be an optional feature, given potential performance implications.

[ermau]

Given the new AppDomain separation, this has gotten a bit trickier. The snapshot will need to be taken in the AppDomain, and represented in a way that can be sent back to the host domain.