Use case-insensitive comparisons to detect whether a species merge is required

Otherwise, importing a species with common name "American Elm" lands in "Merge Required"
because the internal species has common name "American elm".
Use common name to disambiguate multiple species matches

If an imported species row matches more than one internal species, try to pick the one that matches common name

Also remove setting of species fields in the `clean` array -- it's already been done in `validate_string_fields`.
Safety code when looking for a value for species diffs
Make error-correction popup scroll along with its table cell
Improve wording of error messages
Show unknown fields in their original order
When error-correction popup is shown, focus on the input field and select its value.
Show "duplicate species" message in popup

* Show error message from `field.msg` rather than a hard-coded one.
* Update message wording
* Remove stray commented-out line