Fix SimpleObjectHydrator behavior when column not exists in fieldMappings, relationMappings and metaMappings
Merge pull request #593 from norzechowicz/hydrator-fix

Fix SimpleObjectHydrator behavior when column not exists in fieldMappings, relationMappings and metaMappings
[DDC-2300] Fix version xml mapping and serialization of ClassMetadata.
[DDC-1666] Fix bug where orphan removal on one-to-one associations lead to unique constraint errors when replacing an entity with a new one.
Merge branch 'DDC-1666'
Fix DDC-2252
Fix arithmetic priority
Start reorganizing documentation with focus on simplicity.
Reworked parts of the tutorial
Moved tools to Advanced topic, included simple setting up tools in Installation. Reworked CLI tool to print a template when no cli-config.php is defined.
Worked on the Getting Started Guide
Remove models/database first tutorials for now
Move all classes to src/ in tutorial rather than in entities/
Huge refactoring of the Getting Started Tutorial to allow for an earlier success with the simple Product entity.
Add simpler section for 2.4 CLI integration
Fix link in docs
Fix DDC-2090
Merge pull request #619 from FabioBatSilva/DDC-2090

[DDC-2090] Fix MultiTableUpdateExecutor with query cache
adding some more doc and examples for lifecycle event listeners and subscribers
cleanup event subscriber note