Fix Msh2MeshIO:
Fix Msh2MeshIO:

Skip writting data if out is None, write all digits for node coordinates,
write material ids.

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