[BAM] AutoMat

Thanks for the feedback Matthias. I noticed a bug, apparently I accidentally deleted something in the process.

In the found materials filter, if materials are already present in the scene, they should be automatically unchecked after scanning the folder, so that only new materials are created by default.

Do you think it would be more convenient to return this or add an additional button to check the materials in the filter that are already present in the scene?