XFEM: Changed so that the XFEMElementInterface calls giveRealStresses_PlaneStrain() or giveRealStresses_PlaneStress() directly instead of calling giveRealStresses().
IntMatBilinCZ: Implemented giveInputRecord().
XFEM: Introduced XfemStructuralElementInterface.
Merge branch 'master' of https://github.com/Micket/oofem