Improve event source diff sizes

[TonyGermaneri]

Two things can be done to improve diff sizes:

1. Don't update the version field of every vector, just the ones that have changed. Used diffing of each vector to detect which have changed. This occurs on the client for localStorage provider, and on the server for the WSS provider.

2. Change code updates to AST changes. This requires converting the code on the snapshots to AST prior to diff calculations. This would need to happen on the client and server. This would also allow multiple people to work on the same code at the same time.