Take bgm embedded vertices surfaces into account

See merge request !214

Completed: Export multi-Block Structured mesh into CGNS format

See merge request !212

Extension of generic field interface

See merge request !215

new automatic hybrid mesh generation algorithm (tet mesh with quads on boundary,…

See merge request !216

new automatic hybrid mesh generation algorithm (tet mesh with quads on boundary, with pyramid layer)

Fix reader for empty views in msh v2 files

See merge request !213

Take BGM into account in case of embedded vertices. For embedded edges and contour edges, the BGM is already taken into account in their mesh, which is used as starting point to calculate the mesh size on these nodes. However, this cannot be done for an embedded point.

downgrade error to warning of negative jacobians still exist after optimization - it's the same level of information as what one gets when generating the initial mesh (before optimisation)

square_cgns.geo
flow_around_circular_cylinder.geo
cube3d_27blk.geo

Fltk/fileDialogs.cpp
Geo/CGNSOptions.h
Geo/GModelIO_CGNS.cpp

This changes can export 'Multi-block Structured' part of the mesh
(created using Transfinite interpolation) into CGNS format.

The following is the changes between the master and this branch.

1. An option is included in
        Geo/CGNSOptions.h
   The Entry is
        bool structuredMesh;  // = 1 if structured mesh, = 0 if un-structured mesh

2. The above entry is incorporated in GUI option window - Corresponding code change made in file
        Fltk/fileDialogs.cpp

3. Few subroutines and the actual code that write structured mesh in CGNS format is included in file
        Geo/GModelIO_CGNS.cpp

'ctest' was run - All tests Passed

1. An option is included in
        Geo/CGNSOptions.h
   The Entry is
        bool structuredMesh;  // = 1 if structured mesh, = 0 if un-structured mesh

2. The above entry is incorporated in GUI option window - Corresponding code change made in file
        Fltk/fileDialogs.cpp

3. Few subroutines and the actual code that write structured mesh in CGNS format is included in file
        Geo/GModelIO_CGNS.cpp

'ctest' was run - the result was same for both with and without this changes. 01-Nov-2018