Icub-models

Changed

* The python module `icub_models` is now implemented in pure python. This removes the pybind11 dependency (https://github.com/robotology/icub-models/pull/143)

Added

* Implement a machinery to easily access model locations on C++ and Python (https://github.com/robotology/icub-models/pull/130)

Changed

* All Gazebo models installed by icub-models are in SDF format version 1.7. This means that Gazebo >= 11 is required to load them (https://github.com/robotology/icub-models/pull/130).
* iCub3 models (`iCubGenova09` and `iCubGazeboV3`) now have an FT sensor installed in the right upper leg (https://github.com/robotology/icub-models-generator/pull/218)
* The URDF colors of models is not random anymore (https://github.com/robotology/icub-models-generator/pull/217).

Fixed
* Fix missing velocityControlImplementationType parameter in left_wrist_mk2 (https://github.com/robotology/icub-models-generator/pull/213).
* Fix r_wrist_yaw of icub3 generated as continous joint (https://github.com/robotology/icub-models-generator/pull/214)

Fixed
* Fix bug in iCub3 models that made `r_wrist_yaw` a continuous joint (https://github.com/robotology/icub-models-generator/pull/214).
* Fix compatibility of `left_wrist_mk2` with gazebo-yarp-plugins 4 (https://github.com/robotology/icub-models-generator/pull/213).

Changed
* Update iCub3 with feet covers (https://github.com/robotology/icub-models-generator/pull/210).
* Increase metacarpus joint limit of MK3 left hand's thumb (https://github.com/robotology/icub-models-generator/pull/211).

Fixed
* Fixed compatibility of all iCub3 models with gazebo-yarp-plugins 4 (https://github.com/robotology/icub-models-generator/pull/21).

Fixed
* Fixed document on the use of `AMENT_PREFIX_PATH` environment variable (https://github.com/robotology/icub-models/pull/101).
* Fixed wrong default collision on the arms that slowed down Gazebo Classic simulation for iCub3 models (https://github.com/robotology/icub-models/issues/100, https://github.com/robotology/icub-models-generator/pull/208).

Added
* The `hand_mk3` and `wrist_mk2` containing the new version of iCub's hand and wrist, codenamed iCub hand Mk3 and iCub wrist Mk2, have been added to the repo. As this models are still in development, they could change in the future (https://github.com/robotology/icub-models-generator/pull/203, https://github.com/robotology/icub-models/pull/95).

Changed
* The iCub3 models (`iCubGenova09` and `iCubGazeboV3`) have been updated with the new arm covers (https://github.com/robotology/icub-models-generator/pull/202).

Fixed
* The masses of iCub3 models (`iCubGenova09` and `iCubGazeboV3`) have been fixed to be more similar to the one of the real robot (https://github.com/robotology/icub-models-generator/pull/207).