After a mapping change (e.g. the parent-child restructure), existing installs
need to rebuild their index. A DashboardWidget appears on the admin page
warning the admin and showing the command to run. Compatibility is tracked
via the blomstra-search.index-compatible setting.
The flag-based interface (--rebuild etc) became rather convoluted with the changes. Replace this with commands with more straight forward naming.
Also added an explicit 'rollback' action and updated the README.md
Bart van Bragt
Ian Morland
Daniel Klabbers