[!!!][~API] Extbase (Persistence): $query->execute() now returns a plain array of row-arrays instead of an RowIterator. This is a breaking change if you use your own Query object in combination with $querySettings->getRawQueryResult = TRUE.
[~TASK] Extbase (Persistence): Refactored persistence layer (part I). Dropped QueryObjectModel. The Query-Object is now passed directly to the StorageBackend.
[+API] Extbase (Persistence): Implemented methods in() and contains() in the Query-Object. Resolves #6707.
[+FEATURE] Extbase (Persistence): It is now possible to ask contains() for mm-relations, e.g. $query->contains('categories', $category). Resolves #4679.