0025936: Modeling Data - reusable data structure for 2D tesselation (3- and 4-nodal...

0025936: Modeling Data - reusable data structure for 2D tesselation (3- and 4-nodal mesh)

Extension of triangular mesh of Open CASCADE to support quadrangular elements.
A Poly_Mesh class inherits Poly_Triangulation and manipulates quadrangles.
A TDataXtd_SurfacicMesh OCAF attribute is added to support a new surface mesh in OCAF operations.

// Porting of old development (for OCCT 7.1.0) to the current version of Open CASCADE.
// All remarks are checked, regressions are fixed.
// A new test-case is added : caf basic Z1