Added UseBaseClass Doctrine 2 Annotation fixture



Using Single Table Inheritance, is possible have a base entity and a super class that extend this the base. So, if the schema is generated again, what is in the extended class is not lost.

You can see the explanation of this technique here:
http://docs.doctrine-project.org/en/latest/reference/inheritance-mapping.html#single-table-inheritance

I added a option a new option CFG_USE_BASE_CLASS in the Doctrine 2 formatter.