some failure fixed, all tests run successfully
API-PLugin renamed to core, because its more then a api
API-Plugin renamed to core
SAT-Constraint parsing moved to an abstract implementation of
IModelBuilder which is part of the core plugin
Solver interface modifed, now it return after a coll of
getAllConfigurations a set of feature sets. Before the change, it return
a set of feature model sets
Finally add of the csp implementation using choco.
Missing test case added