Add initial version of shared shadow synchronization algorithm
Don't run patch loop if patch is empty. Remove unused shadow in Dom
Fixes for jsonPointer set/add, jsonPatch remove (but only for top level, nested removes for arrays not implemented yet) via mark-and-sweep
Add default handler
Update Memory, Rest, JsonPatch stores, make DocumentView understand promises, reduce snapshotting in jsonPatch--do it in synchronizer instead
Use sync() to simplify form example