Most DMS format parsed by @mapbox/sexagesimal,
add a expandable matcher and two new formats for coordinates in DMS format in search bar
example: `35 11 10.1 , 136 49 53.8` (D M SS format), or `35 11.168 , 136 49.896` (D MM format)
Consolidate localization behavior and init to a coreLocalizer function and singleton
Explicitly support `en-US` locale
Rename coreData to coreFileFetcher and export a singleton rather than using a property of coreContext
Add `apiConnections` property of coreContext to simplify adding a source switcher
Replace some init functions with re-callable, promise-supporting `ensureLoaded` functions
Make coreContext itself load the UI if a container has been specified at init time
Fix code tests
