(only if the current model is not empty: if it's empty it probably mean
we just launched gmsh, and we don't want to delete variables set e.g.
using the -string command line option)

all this open/merge stuff needs to be cleaned up

CGNS I/O rewrite - alpha version

- don't play tricks in Extend1DMesh & co: always follow the option (so we
  can predictbly mix point/curvature lcs with fields)

things down when you have many many surfaces)
- fix out of bound acces in transfinite callback when selecting > 100
entities

orientation in extrusions

Added static routine getInfoMSH - returns name and No. vertices for a
MSH type

Addes MSH_NUM_TYPE - number of MSH element types