Issue #2939724 by ryanhayes, joachim, Samvel, andrewmacpherson, sacha@wellborn.co.uk, Adam_Moulsdale, rachel_norfolk: wrong variable name in sample code

(cherry picked from commit 441f198b)

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2344831 by martin107, jhodgdon, tstoeckler, Mile23: Document behavior of Drupal/Core/Database/Query/SelectInterface::__toString()

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2068655 by Berdir, chx, martin107, longwave, webflo, damiankloip, lokapujya, JacobSanford: Entity fields do not support case sensitive queries

Issue #2057809 by StephaneQ, Berdir, chx, dawehner: Fix up param/return documentation in database API

Initial move and rename of database classes to PSR-0 namespaces.  So far only MySQL has been converted.