v2.0.0

This is a major update since our publication:

1. The model has been re-trained with a duplicated structures removed, and additon of ~30K experimental MOF structures.
2. During the re-train, coordination shell features are removed from the node features while bond distances are added as an edge feature. Hyperparameters of model has been re-optimized.
3. Chemical bond radii for each element pair are now used for bond table construction inplace of the Isayev's nearest neighbor algorithm. This speeds up the bond table construction significantly (since no Voronoi analysis needed) while proceducing the same bond tables.