* Add API to download formal charges for missing templates

* Use formal charges in _createForceField

* Add tests for formal charges

* Download charges from CCD when attempting to solvate

* Fix charges for default ion atom names

* Simplify formal charges logic

* Expose downloadFormalCharges and remove getAllFormalCharges

* Unify and cache CCD lookups

* Fix bugs

* Cache a failed CCD download

* Remove old formalCharges argument from registerTemplate

* Only attempt to download formal charges if they will be used

* Add SMILES to CCD cache

* Clean up new code and add docstrings

* Only apply formal charges when all and only atom names match between the CCD and PDB

* Allow formal charges to be set with or without leaving atoms

* Address concerns from code review

* Remove leftover reference to checkCache

* Do not cap chains in test_charge_and_solvate

* Add forceField optional argument to addSolvent

* Cap with glycine in tests

* Add another test with a charged ligand

* Cosmetic commit to re-trigger tests

* Update pdbfixer/pdbfixer.py