Several wording changes applied

- Changed info note in handle names split page
- Changed info node in handle children split page
- Changed 'species' with 'taxon'/'taxa' to refer to any taxonomic level
-  Replaced simple ordering in the split outputs page with 'Taxon 1', 'Taxon 2' etc.
- Renamed labels in the split outputs page
- Changed global selection info note
- Added more information in the nomenclature notes template for an upgraded taxon
- Children ordered by name in the children page
- Renamed 'Upgraded taxon' to 'Existing subspecies' in the split outputs page