Add TICON-4 data

[bkeepers]

This pull request adds a script to import stations from TICON-4, TIdal CONstants based on GESLA-4 sea-level records.

It includes 4,838 global stations.

$ tools/import-ticon
Done. Created 4838 stations.

TODO:

• Resolve duplicates between NOAA/TICON. It might make sense to just skip any that are from NOAA in TICON, but I want to compare the list and see if there are any dinfferences.