to fix configure when GMOCK_FOUND is not set.

for a missing cast in googletest on 18.04

for eigenpy v2

this can't depend on both:
- simulation/gazebo-ros-pkgs
- wip/prf-gazebo-ros-pkgs{,-melodic}

as they conflict.

This "controller_interfaceConfig.cmake" is not a part of this package.

To fix tests with eigenpy v2

Changes since v4.8.1:
- [Tests] switch to numpy arrays

Changes since v1.0.0:
- added few cost functions related to forces and impulses (e.g. friction-cone, com impulse)
- improved the display tools (friction cone, contact forces and end-effector trajectories)
- fixed a problem in the printed message by the callback
- fixed a problem in the box-qp
- improved the box-ddp
- added a new solver called box-fddp
- added extra examples (box-ddp vs box-fddp, taichi task, humanoid manipulation)
- added a script for automatically updating the log files
- checked that all examples runs in the CI (for release mode only)
- improved the quadrupedal and bipedal examples by adding all the constraints
- improved the efficiency in differential free-forward dynamics
- added extra setter functions in action models
- improved efficiency in all solvers (removed extra computation)
- improved plot functions
- fixed a bug in few notebooks

Changes since v0.3.1:
- [Python] Fix binding of Piecewise.curve_at_index
- Replace assert with exceptions
- install header python/python_definition
- Fix when t_min == t_max
- Add API to get bezier waypoints and SE3 translation/rotation curves

Changes since v4.8.0:
- moved srdf files to example-robot-data

Changes since v3.1.1:
- Migrate universal robot srdf files from hpp-universal-robots.
- Include ur srdf into loadUR
- Added effort limits for reduced models
- Fix compatibility with numpy matrix

Add scripts/start_talos_gazebo.py
This allows launching gazebo with a more precise sequence than roslaunch.

Changes since v0.2.0:
- Improved logging

Packaging changes:
- removed patches aa, ab, applied upstream

ref https://github.com/loco-3d/crocoddyl/pull/675

Make the package compatible with bionic/Ubuntu 18.04 LTS
Fix bionic detection

Changes since v0.0.13:
- write "pyrene.urdf" in /robot_description parameter.
- remove temporary files from tarball

As it uses std::weak_ptr

Changes since v1.1.1:
- fixed .pc
- updated CMake

Because, with a recent CMake, if doc/header.html is provided and the
build folder is the root folder, this file gets overwritten by itself,
disappears, and therefore can't be installed.

fix configure on Arch for ignition-common1

to fix build of wip/prf-ros-controllers on 16.04 & python3