exception refactoring to only use doctrine exceptions
Merge pull request #322 from doctrine/exception-cleanup

exception refactoring to only use doctrine exceptions
First steps with new QB API
Finished AbstractNode
Building in more nodes
Added all join stuff.

- next step: test all the join stuff
Added tests for join

- next: JoinCondition tests
Added JoinCondition tests
Added property + select
Propvisional where
Added constraints

- todo: Test constraints
Fixed tests
ADded provisional operand factory

- @todo: All the operand stuff
Added operand stuff
Added ordering
Fixed validation
Added some example API tests
All tests pass
First essayage on PHPCR walker

- Notes on QB API:

 - Selectors mandatory? I think so, they should precede other args.
Started converter