new "merge" option in `convert_mesh.py` - remove duplicate vertices
new "merge" option in `convert_mesh.py` - remove duplicate vertices

vlukes/sfepy,vlukes/sfepy,rc/sfepy,lokik/sfepy,lokik/sfepy,BubuLK/sfepy,lokik/sfepy,sfepy/sfepy,vlukes/sfepy,rc/sfepy,BubuLK/sfepy,rc/sfepy,sfepy/sfepy,sfepy/sfepy,BubuLK/sfepy,lokik/sfepy