Fix cloning with arrays

fix: merging a field with empty array update doesn't overwrite. (#5)

Adds a failing test for this case and introduces a fix.

Properly support cjs files

Renames index.cjs.js to index.cjs to properly support how nodejs resolves module type.

Fix parent typing

v0.10.1

fix: some more ergonomic typing for ModelParent

Switch to rollup builds

• Start using rollup for multi target builds

Rework some APIs

• Better and more functional extension API
• Much better implementation of toRef

Fixes and API tweaks

Merge pull request #2 from jadengis/johndengis/fix-typedefs

fix type defs