CompoundMesh does not work with FCL

[rjoomen]

CompoundMesh does not work with the FCL collision checker. I suppose it is because for Bullet, one CompoundMesh is added as one compound object, whereas for FCL, one CompoundMesh is added a multiple objects.

I've taken a look, it seems FCL does not support compound objects, apart from BHVModel, which only supports meshes or pointclouds as submodels.

And for reference, neither does HPP-FCL: #340, #448.