Release 4.0.0

Breaking changes

• The merge() method has been improved:
  • Merging is now deep by default
  • Merging mode can be changed to "shallow", "set" or "delete" using a _merge property
  • Arrays can now be merged using objects where the keys are the array indices. Items can be updated, merged, added, inserted, appended, prepended or deleted.
  • The merged value can now be of any type
  • TypeScript types have been updated accordingly