Mesh collection during import is redundant

[grebz-dev]

https://github.com/cadop/HumanGenerator/blob/386f3d27e7d90b29f3fb4905768c61ee794525da/exts/siborg.create.human/siborg/create/human/human.py#L471

https://github.com/cadop/HumanGenerator/blob/386f3d27e7d90b29f3fb4905768c61ee794525da/exts/siborg.create.human/siborg/create/human/human.py#L662

Both collect meshes redundantly. Should use mh_meshes passed as argument.