quad mesh bug fixes

Geo/GFace.cpp

Geo/MQuadrangle.cpp

Mesh/BackgroundMesh.cpp

Mesh/Generator.cpp

Mesh/directions3D.cpp

Mesh/meshGFace.cpp

Mesh/meshGFaceDelaunayInsertion.cpp

Mesh/meshGFaceDelaunayInsertion.h

Mesh/meshGFaceOptimize.cpp

Mesh/meshGFaceOptimize.h

Mesh/meshGRegionDelaunayInsertion.cpp

Mesh/simple3D.cpp

Mesh/surfaceFiller.cpp

benchmarks/hex/cube.geo

utils/converters/autocad/dxf2geo.cpp