Move Vf and Vmin from Body`s parameter to Body->state.

Only for compilation, where YADE_LIQMIGRATION is enabled.
Replace struct intReal by standard std::pair
Prevent returning of a real value from void-function.
Fix probably a wrong using of if-condition.
Minor fix of using of std::abs function.
Drop some if-conditions, which have always constant value.
Drop default inclusion of DFNFLOW.
Add some missing #ifdef YADE_CGAL.
Fix check-script for LIQMIGRATION.
Drop -frounding-math compiler flag from FindCGAL.