This was taking a lot of time at app startup.
Instad now we resolve and index only the include and exclude parts.
We can still determine the valid locationSets at runtime in `locationSetsAt()`
by checking the `_locationIncludedIn` and `_locationExcludedIn` caches.
This also upgrades the locationManger to an ES6 class.
This also includes some hacky code in nsi.js so that the NSI will continue to work.
The NSI matcher can build its own location index, but it doesn't need to do this.
We monkeypatch a few of the matcher collections to work with the new LocationManager.
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
Rename IssueManager to coreValidator
Rename disconnected highway to disconnected way
Rename highway almost junction to almost junction
Rename mapcss checks to maprules
Rename deprecated tags to deprecated tag
