Pgdtools

Classification of presolar SiC grains has changed to be in line with the 2025-03-10 version of the SiC database.
The definitions for X, C, D, and N grains have changed, now allowing 14N/15N ratios up to solar (441).

Current database versions (updated individually without required `pgdtools` update):
- SiC: 2025-03-10
- Graphites: 2025-03-24

First release of the package with the Mai 2024 databases for graphite and SiC grains.
Classification scheme as described in [Stephan et al. (2024)](https://doi.org/10.3847/1538-4365/ad1102).