[scolv] Add Nearby Cities tab

[comoglu]

Adds a Nearby Cities tab to scolv that lists cities near the current origin, sorted by distance, and allows setting a descriptive region name on the event without leaving scolv.

Depends on: SeisComP/common#189 — extends CityD with country, AdminRegion (state) and type. This PR should be merged after that one.

Features

• Table showing Name, Type, Region, Country, Distance (km), Direction, Population and capital flag (★)
• Capital cities rendered in bold
• 16-point compass direction
• Correct numeric sorting on Distance and Population columns
• Set as Region Name — sets a REGION_NAME EventDescription on the current event via notifier to the EVENT messaging group; five selectable format templates
• Cities sourced from the built-in cities.xml via SCApp->cities() — no external file dependency

Configuration (scolv.cfg)

Parameter	Default	Description
cities.maxDist	1000 km	Search radius around origin
cities.maxCount	20	Maximum cities displayed
cities.minPopulation	10000	Minimum population (capitals always shown)
cities.useFullState	true	Show full region name vs abbreviation; falls back to country name when no region available

Region column display logic

City data	useFullState=true	useFullState=false
Has state with abbr and name	Full name (e.g. "New South Wales")	Abbreviation (e.g. "NSW")
Has state with name only	Full name	Full name
No state, has country	Country name (e.g. "Türkiye")	Country name

Relationship to cities.xml

cities.xml currently carries name, lat/lon, population, countryID, category, country, state and type. The enrichment tooling is available at https://github.com/comoglu/cities-xml-update.

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[gempa-jabe]

Can you please rebase against the latest main branch? This PR includes dozen of old commits.

[comoglu]

Done

[gempa-jabe]

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[gempa-jabe]

Actually I am not in favour of adding an additional JSON file as dependency to make that work. Adding the missing attributes to cities.xml might be the better option but I am not sure right now if we could gather all the required information from the data sources?

[comoglu]

I had the same worry, but I didn't want to change cities.xml because it has been there for a long time. It might be time for it to change.

[gempa-jabe]

You have updated the content some time ago anyway. So I don't see an issue with extending its model to other attributes. Not sure how big this XML will get afterwards and if it is worth to keep an XML file at all or if it would be better to use an SQLite3 database. The XML file could take an (tremendous) amount of memory at each client who is reading it. Dealing with another source of information, even in the MariaDB/PostgreSQL database itself, could be a better approach. As you say, it has been there for a long time and sometimes things are about to change for the better.

[comoglu]

Yes, I'm adding more to the XML content. I use the same source to update the current XML file. Let me see how big it can get.

[comoglu]

I will be touching coord.h and coord.cpp to add new fields as well.

[comoglu]

You have updated the content some time ago anyway. So I don't see an issue with extending its model to other attributes. Not sure how big this XML will get afterwards and if it is worth to keep an XML file at all or if it would be better to use an SQLite3 database. The XML file could take an (tremendous) amount of memory at each client who is reading it. Dealing with another source of information, even in the MariaDB/PostgreSQL database itself, could be a better approach. As you say, it has been there for a long time and sometimes things are about to change for the better.

the cities XML is now ~18MB