hpp-pinocchio, hpp-constraints, and hpp-walkgen are on 4.9.1.

This reverts commit 8d4babc9.

  - eigenpy: 1.5.1 -> 2.3.2
  - pinocchio: 2.4.3 -> devel

Update Pinocchio version.

[Makefile] Add extra flag for gepetto-viewer for Qt5

Changes in HPP-Core need version 2.2.3 of Pinocchio.

  This cmake variable is planned to replace variable DISABLE_TESTS defined
  in the cmake submodule.

  - example-robot-data is required to run hpp-core tests.

as 18.04 is now the main supported distribution

  Will work in ubuntu-18.04, maybe not in ubuntu-16.04.