Rework Latitude and Longitude regex matching

[kasarit]

This issue applies to both Latitude and Longitude classes.

super("^(?<latitude>[NS]\\d+)$", prio);

The named group is obsolete, as it matches the whole regex. I'd suggest to either

• split the expression to proper groups, e.g. "^([NS])(\\d{1,3})(\\d*)$" (with or without names) and read only groups, or
• have a simple regex "^[NS]\\d+"$ and read characters/substrings at know indices.

It also may be wise to be strict with number of digits, e.g. "^([NS])(\\d{3})(\\d{2})?$" as this is what the EU 373 + 1338 and ICAO Annex 3 say. And we cannot be certain of the correct interpretation if number of digits mismatch - it may be better to raise a syntax error.

Originally posted by @petringo in #117 (comment)