Update robot library

[gonzalocasas]

Cleanup and update of the robot library + some fixes!

• Relies on Handle non-surface Collada geometry compas_robots#34 for a fix to DAE parser required by UR16e dae files
• Remove ABB IRB120 because it was not supported by the analytical solvers and because it is weird also
• Refreshed all UR robots and added missing ones directly from the original ROS support packages. This time, not converting the DAE to OBJs so that we preserve materials.
• Added Staubli TX2 60L because we had the analytical solver already, so it's kind of consistent that we have models for all the analytical solvers present
• Switch to DAE for Panda (again, to bring in materials)
• Fixed a limitation for continuous joints when fitting to bounds.

What type of change is this?

• Bug fix in a backwards-compatible manner.
• New feature in a backwards-compatible manner.
• Breaking change: bug fix or new feature that involve incompatible API changes.
• Other (e.g. doc update, configuration, etc)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you're unsure about any of them, don't hesitate to ask. We're here to help! This is simply a reminder of what we are going to look for before merging your code.

• I added a line to the CHANGELOG.md file in the Unreleased section under the most fitting heading (e.g. Added, Changed, Removed).
• I ran all tests on my computer and it's all green (i.e. invoke test).
• I ran lint on my computer and there are no errors (i.e. invoke lint).
• I added new functions/classes and made them available on a second-level import, e.g. compas_fab.robots.CollisionMesh.
• I have added tests that prove my fix is effective or that my feature works.
• I have added necessary documentation (if appropriate)

[gonzalocasas]

/cc @jf---