fixed problems with joined inheritance and composite keys

SchemaTool now creates all Id columns not just only the first one.
Insert statement for child entity now contains parameter for additional key columns only once.
inheritance with composite keys

added tests for single table inheritance
Unit tests: cleaned up outdated / unused / commented out code.
Failing test for DDC-2306

As of DDC-1734, proxies should have null identifier when the UnitOFWork
refreshes entities and replaces them (marking them as un-managed).
The problem here is that refreshes on entities with same identifier
but different type are still considered same, and the UnitOfWork discards
the proxy instance instead of ignoring it.
Fixing DDC-2306
Adding failing test for DDC-2230

Proxies that implement the Doctrine\Common\PropertyChangedListener are getting eagerly
initialized because the UnitOfWork injects itself into them after they are created.
The test currently fails for what described above, and also verifies if the UoW
is correctly injected in the proxy during lazy loading.
Applying fix for failing test for DDC-2230
Remove dead code
Merge pull request #585 from Ocramius/hotfix/DDC-2306

Hotfix/DDC-2306
Merge pull request #589 from Ocramius/hotfix/DDC-2230

Hotfix for DDC-2230
Clarified versionadded on EntityListeners feature.
Add versionadded tags to many ffeatures in the docs.
Dont mention 2.2 version in headers anymore.
Update theme
Fix versionadded for IDENTITY()
Fix SimpleObjectHydrator behavior when column not exists in fieldMappings, relationMappings and metaMappings
Use inflector for add/remove methods
Merge pull request #594 from v3labs/master

Use inflector in EntityGenerator
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.