moving axed constraint
merge
moving axed constraint
correct required constraint
adding virtual constraint
Merge branch 'master' of
https://github.com/genericsystem/genericsystem2011.git

Conflicts:
	genericsystem-impl/src/main/java/org/genericsystem/impl/core/EngineImpl.java
	genericsystem-impl/src/main/java/org/genericsystem/impl/core/GenericImpl.java