several bug fixes

Geo/GEdge.cpp

Geo/GFace.cpp

Geo/GFace.h

Geo/GModel.cpp

Geo/GModel.h

Geo/GeoInterpolation.cpp

Geo/GeoInterpolation.h

Geo/MElementOctree.cpp

Geo/MTriangle.cpp

Geo/STensor3.h

Geo/gmshEdge.cpp

Geo/gmshEdge.h

Mesh/BackgroundMesh.cpp

Mesh/BackgroundMesh.h

Mesh/Field.cpp

Mesh/HighOrder.cpp

Mesh/highOrderSmoother.cpp

Mesh/highOrderSmoother.h

Mesh/meshGFace.cpp

Mesh/meshGFaceOptimize.cpp