v7.0-beta.51

* Added `formTokenRequest` property to OpenId config for use with AWS authentication. This forces the use of a form request when fetching tokens.

* Issue **#1824** : Fix for search hang when extraction is requested but no search pipeline is provided.

* Issue **#1083** : Added `any()`, `first()`, `last()`, `nth()`, `top()` and `bottom()` selection functions to select child values of grouped items.

* Issue **#1837** : Added `joining()` function to concatenate supplied fields in child rows.

* Issue **#1784** : Several functions were previously prevented from working on results from aggregate functions but are now applied regardless.

* Fix config file validation not working when hot loading config file changes.

* Change config file validation to be the first thing that happens on boot.

* Fix error when empty branches are in the config file.

* Add `pipeline.referenceData.getLmdbSystemLibraryPath` prop to support provided LMDB binary.

* Change extraction location of bundled LMDB binary to be the same as the store files.

* Change default value for `pipeline.referenceData.maxPutsBeforeCommit` to 0 (i.e. don't commit mid-load).