* Add simplified double pendulum

* Add description to urdf, loader and unittest

* Fix format

* Fix format for unittest

* double pendudum: update credits

Co-authored-by: Justin Beri <justin [dot] beri [at] csiro [dot] au>
Co-authored-by: Justin Beri <justin.beri at hdr.qut.edu.au>
Co-authored-by: Guilhem Saurel <guilhem.saurel@laas.fr>

* added Articulated soft robot loader and description

* removed the unneccesary files and the deprecated loader function

* added license and readme

* renamed the readme file and added these files in twodof robot description

* remove use less file

* remove useless file

* Update test_load.py

* removed useless folder and plugins from the urdf

Co-authored-by: Justin Carpentier <justin.carpentier@inria.fr>

* Make double_pendulum's joints unbounded revolute (continuous)

* Add continuous (SO(2)) variant of double_pendulum

* Remove update to deprecated function; inherit from DoublePendulumLoader

* Add unit test

* [cassie_description] initial commit

* [cmake] update

* [cassie.sdf] change mesh path relative to example-robot-data

* [cassie_description] move meshes up folder

* [cassie-loader] create loadCassie function for load with sdf

* cassie srdf: standing pose

* [cassie_loader] use robotloader

* add unittest. won't yet work before pinocchio3

* Update unittest/test_load.py

Co-authored-by: Guilhem Saurel <guilhem.saurel@laas.fr>

* ci fixes: flake8 + unittest missing module

* fix test

Co-authored-by: Rohan Budhiraja <proyan@users.noreply.github.com>
Co-authored-by: Guilhem Saurel <guilhem.saurel@laas.fr>

ref #67

In case we actually have a 1.0kg body, we can still put its name into
the one_kg_bodies arg.

And activate tests again

to avoid a dependency to https://github.com/stack-of-tasks/talos-data/
in many packages

Which lead to find that double pendulum, hector and iris were not
tested.

Writing a test for hector raise:
> IOError: hector_description/robots/quadroto_base.urdf not found

Which lead to find that __main__ was missing the variations of icub &
ur5

In the previous version, changing NQ / NV, wouldn't change the test
results.

Also, we had a test checking that talos arm had a free flyer,
and another test checking that talos arm didn't had a free flyer.
Both were passing.

when it was useless otherwise

PYTHON_INSTALL_ON_SITE does the PYTHON_BUILD and the INSTALL, but they
require to have the same arguments. Then, we have to put the CMakeLists
in a parent folder of the module, as `python`, or `bindings/python`.