UTF-8 Support and Compatibility

We only need to worry about explicitly supporting UTF-8 where we manually process strings.  Otherwise encoding is handled by the source or destination of strings (e.g. the shell for the CLI, and files for param codecs).

Both JSON and YAML support UTF-8, and the parsing libraries we use take UTF-8 as the default encoding.

Areas for concern:
- [ ] `param/param_helpers`
