CREO2URDF – Correctly handle the joint definition when using CSYS

[Nicogene]

In creo2urdf the linkFrames parameter is optional, it allows to specify which frame has to be used as the reference frame for a specific link.

To be compliant with the urdf specification, this frame has to lie on the axis of the joint of which the link is the child link.
If not specified we use the default CSYS that may have an offset w.r.t the axis of the joint, this means that the joint right now might rotate "outside" the link

✔️ We correctly handle it

❌ We do not handle it correctly

In:

• #97

a lot of debugging has been made but unfortunately something is missing

[Nicogene]

Thanks to:

• robotology/idyntree#1193

this issue now is way simpler!

[Nicogene]

Thanks to the PR of @traversaro in idyntree now we can export the icub urdf!

cc @pattacini @maggia80 @fiorisi @Lawproto @salvi-mattia @mfussi66