[FEATURE] introduce nodeType:show command
[!!!][FEATURE] make mapping configurable in NodeTypes.yaml

NOTE: the indexing / querying side has not been adjusted yet!
[FEATURE] when triggering an import, allow to completely recreate the index
[TASK] extract method "createIndexIfNotExists"
[FEATURE] completely rewritten Node Indexer

... configurable through YAML

... now, the searching still needs to be adjusted
[TASK] adjust query generation to updated field names

With this change, the start page works again as it should
[TASK] Merge branch 'master' into dev-nodetype-mapping

Resolved trivial conflict in NodeTypeMappingBuilder.php
[TASK] Some cleanup to new indexer/mapping code