[GH-512] Added addParameters() to Query and QueryBuilder

This issue is created automatically through a Github pull request on behalf of jappie:

Url: https://github.com/doctrine/doctrine2/pull/512

Message:

This method behaves like setParameters() before version 2.3:
It will add new parameters to the collection, and override any existing positions/names.

It can take a Doctrine\Common\Collections\ArrayCollection with Doctrine\ORM\Query\Parameter objects, as well as a plain array with key/value pairs, as argument.

This will greatly ease the upgrade to Doctrine 2.3, because you only need to perform a project-wide replace of setParameters with addParameters, in stead of going into your code and determine if calls to setParameters are ok or need refactoring.

I've also added unit-tests to maintain integrity.