Enabling Eigen in travis

[dcoeurjo]

PR Description

Update of the travis scripts to enable Eigen tests. This would enables unit-test for the DEC package for instance.

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)

[dcoeurjo]

@kerautret , @elcerdo I have refactorized travis script (with child scripts in .travis/ folder). It is clearer now and the Eigen install seems to be ok now (version 3.2.10).

@elcerdo can you please have a look to the DEC issues with this eigen ?

On mac, there is an issue with libqglviewer but it is not related to Eigen issues.

[dcoeurjo]

ping @elcerdo

[elcerdo]

DEC tests seams to be fixed. Remaining Travis failures are caused by compilation/cmake errors.
FYI tests failed because there has been a change in boost::hash_range between the antiquated Travis boost version and reasonably recent desktop boost version.

[dcoeurjo]

Ok. Travis is fine again.

[dcoeurjo]

mreging