Using Dscribe as CPP libs.

[Neo-Teyrall]

Hi, I'm not sure if this is the right place to submit this.

I've been working on integrating the Soap descriptors into a CPP software I'm developing. However, I encountered some difficulties due to the Python interfacing with pybind11, making it challenging to use the library correctly and preventing multithreading for computing different descriptors in parallel. To address this, I started to rewrite the code by removing the Pybind11 variables.

I've successfully completed this work for the SOAP polynomial and SOAP GTO descriptors. Additionally, I've created a CMakeFile for compiling the project in a specified directory rather than the Python install directory.

Would it be possible to add this contribution to the Git repository? I'm open to suggestions on how these modifications should be integrated—perhaps in another branch. Your guidance on this would be appreciated.

PS : Note that code factorization has not been processed yet between method using Pybind11 variables and method using CPP variables !