Add Obj format in MeshReader including colors

[kerautret]

PR Description

Add Obj format in MeshReader including colors.
All DgtalTools viewer will be able to read and display obj mesh without any changes.
It is based on the same code of SurfaceMeshReader with adaptation by removing normal read and adding mtl file reading to recover colors.

• It fix an error on obj file with relative face reference (also applied in SurfaceMeshReader)

Checklist

• Unit-test of your feature with Catch.
• Doxygen documentation of the code completed (classes, methods, types, members...)
• Documentation module page added or updated.
• New entry in the ChangeLog.md added.
• No warning raised in Debug cmake mode (otherwise, Travis C.I. will fail).
• All continuous integration tests pass (Travis & appveyor)

[kerautret]

Codacy issue looks a bug or I miss something...
The two spaces are well here:

[dcoeurjo]

travis is back...

[dcoeurjo]

Thx for the PR. Just some comments

[dcoeurjo]

Please use the clang format to have the proper code formatting (there is a .clang-format in the project)

[dcoeurjo]

Please use the clang format to have the proper code formatting (there is a .clang-format in the project)

[dcoeurjo]

Ok the Exclude is not working...