Merge Python 3 porting.

diff --cc doc/salome/examples/blsurfdemo.py
Simple merge

diff --cc src/BLSURFPlugin/BLSURFPluginBuilder.py
Simple merge

diff --cc src/BLSURFPlugin/BLSURFPlugin_BLSURF.cxx
Simple merge

diff --cc src/GUI/BLSURFPluginGUI_HypothesisCreator.cxx
Simple merge

diff --cc tests/test_periodicity_reflexion_2D_precad.py
Simple merge

diff --cc tests/test_proximity.py
Simple merge

diff --cc tests/test_remove_tiny_edges.py
Simple merge