WIP commit of fixed statem test and some bugs it now finds
Fix reset to not advance the timestamp

Add tiebreakers for merge where the timestamp is equal
Reset on lww register resets the timestamp to zero

Discuss: this is now non-monotonic, but in a map remove | update
where update is temporally before the remove, it means the update
value wins.
Fix map model to account for reset remove

Use the remove history to create a tombstone
Removed zorset and rwmap for now
Add set operations `update`, `add_all`, `remove_all` to OR-Set

Delegate the VVORSet EQC call backs to the ORSet callbacks as
they are identical.
Quickcheck the `update` bulk operation on OR-Set impls

Fix bugs in code and model found by testing
Fix reset fun to use correct update tuple for removing fields
Merge tombstones in the Map

If two tombstoned replicas merge the tombstone is lost. A bug in the
map meant that only fields that were present in at least one replica
were persisted.

A side effect of merging tombstones and keeping them is that in some
edge cases a `reset` can be magnified.

Imagine replicas A, B, and C. A updates a counter at field F by 10
B updates a counter at field F by 10. A and B merge.
A removes the counter at F (resulting in actor A decremting by 20)
B removes the counter at F (resulting in actor B decremening by 20)
C inrements a counter at F by 10.
A, B and C merge. The counter at F is present and it's value is -10.

This makes sense as a remove is also a decrement of all seen values
but may confuse a user.

Sets are unaffected as their removes are idempotent.