Removing Dependency on Momentum for Ease of Installation

[AtlantixJJ]

Hi authors,

Thank you for releasing this very useful tool. However I found it very hard to install, typically the momemtum package needs pytorch 2.8.0 to install but I think many servers do not support this version due to CUDA driver version mismatch. In fact, the only thing required from momemtum in this repo is a load fbx function. It would be much easier to use if you can remove the dependency of momemtum. Thank you!