* fix json for Path, FilePath, and DirectoryPath objects, fix#473
* convert to single spaces
* assert result to a string
* Update test_json.py
* encode entire Path hierarchy the same way
* fix: serialize secrets to json, fix#462
* feat: adjust documentation for secretstr.
* feat: undo unnecessary changes. keep tests.
* fix: tests were broken, now they're fixed again.
* feat: add display fn to SecretStr and SecretBytes, to be used for json output.
* fix: minor typo.
* fix: last few comments.