remove cruft
new class CitiesFile is a home for the writing and reading of the cities file
fetch city information on startup
main activity listens for changes to prefs, gets new city
CityInstance creation based on JSON tolerant of crappy json
routeserver uses url and not domain/prefix tuple, so that you can easily configure to use route server on a different domain, and moving towards changing map state on changing city
convert to using lat/lon in preference to persist map state, and set it when city pref changes
always persist map prefs on change of map