Doc mesh and tube mesh generation

[kerautret]

Module doc add with some static method to generate tube mesh and height field mesh

[coveralls]

Coverage decreased (-0.23%) to 90.1% when pulling 86ac539 on kerautret:DocMeshAndFct into 697ef51 on DGtal-team:master.

[coveralls]

Coverage increased (+0.01%) to 90.34% when pulling fe7b605 on kerautret:DocMeshAndFct into 697ef51 on DGtal-team:master.

[dcoeurjo]

remove ? ;)

[kerautret]

Thanks for all remarks that I agree (and sorry for the various typos).
I also add some edits on iterators and the previous commit 9dfc265 also contains some edits on (const/not const getVertex)

[kerautret]

To finish, I also added an new method to display tube with variable radius...

[dcoeurjo]

I'll have a look to the build . thanks for the edits

[dcoeurjo]

Build and test are fine. thanks.