Unit tests: cleaned up outdated / unused / commented out code.
Remove dead code
Fix SimpleObjectHydrator behavior when column not exists in fieldMappings, relationMappings and metaMappings
Fixed broken code block in documentation
Missing link to a cookbook in the docs

The cookbook existed in the docs but there was no link to it in the docs.
Reverted incorrect typo fix -_-
Typo
Removed unnecessary <?php from the docs
Merge pull request #596 from mnapoli/patch-2

Missing link to a cookbook in the docs
Merge pull request #599 from alexcarol/fix/docs

Removed unnecessary "<?php" from the docs
Added $isIdentifierColumn documentation

I've added the documentation of the argument $isIdentifierColumn since in case of foreign composite keys it doesn't 
Added 'contains' comparison
Added composer.lock to .gitignore
Fixed typos
Merge pull request #607 from pborreli/typos

Fixed typos
Fixed typo
Merge pull request #608 from pborreli/patch-1

Fixed typo
Fixed typo.
Merge pull request #609 from haroldb/patch-1

Fixed typo.
[BUGFIX] Correct link to Functions, Operators, Aggregates

This fixes the in-page link to the Functions, Operators, Aggregates
section.