THIN_HISTORY - Reinstate incarnation encoding in ChangeSets, but remove from index keys (#443)

* Cutting incarnation out of history and changeset keys

* Rollback the remove of incarnation only in changesets

* Fix linter

* Remove debug printing

* Reinstate encoding of incarnations in the ChangeSets

* Fix linter

* Fix linter

* Fix DefaultIncarnation

* Fixes

* Fix lint

* Fix to history writing

* Fix linter

Author: AlexeyAkhunov