Idea: modify sync() to be a first class feature that intelligently keeps 2+ forms histories in sync

[dxinteractive]

When sync is used, people shouldn't also use onDerive() between the same forms, but making people do this is a tough ask, especially if different parts of a system may be deriving to each other. Instead make Dendriform have a register of sync groups, which sync can add to, and check which members of each have synced after deriving is complete, and throw no-change's in the others.

[dxinteractive]

Rename this, sync sounds like a two-way derive but its only about keeping history in sync.

[dxinteractive]

WIP https://github.com/dxinteractive/dendriform/tree/feature/sync-groups

[dxinteractive]

Released in 3.4.0