Spawned from #281:

1. more compact sets can be produced by trying out some random iterations; this is what my reference implementation in ERKALE does.
2. in J. Chem. Theory Comput. 19, 6242 (2023) I showed that the automatically generated sets can be significantly contracted without losing accuracy; one just needs to do a singular value decomposition
3. for straightforward ground state total energy calculations, one can throw out the high-angular momentum functions