Feature/meshstructured

[vincentchabannes]

• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes?
• Have you successfully run the Feel++ testsuite with your changes locally?
• Have you written Doxygen comments in your contribution ?

---

MeshStructured features :

• 1d/2d/3d with hypercube element (TODO : Simplex)
• geometry currently available: hyperrectangle. The setup of the geometry is given by a json file, see examples in test_meshstructured. (TODO : other shapes as for example an arbitrary Quadrangle(2d) or QuadrilaterallyFacedHexahedron(3d) by using geo transformation of hypercube).
• partitioning currently available: striped one direction (TODO : by block)

@prudhomm It will break some code that uses MeshStructured :

• template parameters of class MeshStructured
• constructor args

[prudhomm]

Is there a test for the case with coordinates ? I found one but it is commented out

[prudhomm]

the test does not work with coordinates ?

[vincentchabannes]

the coordinates test is here. These lines commented was a hbf test but it was always commented before my changes.

[prudhomm]

nice job for refactoring this