geocode: major refactor - still WIP

- call it Geonames cities index, not database
- promoted index subcommand operations to subcommands for better input mgmt/error-handling
- added `index-reset` subcommand
- removed `--no-headers` option, headers are required
- added logic to handle column to geocode not provided when using stdin
- all index subcommand are now working
- use winfo! macro for updates to log:info and stderr when running index subcommand