Unit tests: cleaned up outdated / unused / commented out code.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
Reverted incorrect typo fix -_-
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
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.
Mention flush cannot be called inside postFlush
[DDC-2282] Fix pagination problem with SQL Server.

ORDER BY removed from all count queries when on SQL Server
Fixed SQLServer ORDER BY problem in paginator CountOutputWalker
Added test to check query with ORDER BY and SQLServerPlatform
Merge branch 'GH-572'
Merge pull request #610 from afoeder/patch-1

[BUGFIX] Correct link to Functions, Operators, Aggregates
Don't add empty expression to another one
Merge pull request #602 from alex88/patch-1

Added $isIdentifierColumn documentation