Exmol

* Added new quiet mode to disable progress bars

Possibly Breaking changes
* Switched to SELFIES v2.0, so custom alphabets will need to be ported.

Changes
* Removed "experimental" tag from Chemed and Custom methods

Bug fixes
* Type annotations now pass `mypy`
* Paper models now generate SVGs correctly and fixed token issues

* Changed behavior of `num_samples` so that it is not affected by mutation count in STONED

* Fixed SMILES escaping in URL in chemed

* Fixed similarity float vs int in chemed

* Added custom lists for counterfactual source (contributed by maclandrol)