Replaced showBoxes with preIsValid, coIsValid. There are Travis County voting precincts outside the city, so you can conceivably h
ave a precinct overlay to display but not a council district overlay.
Renamed "cdID" to "coID", because all the other council district variables start with "co".
Moved navigator.geolocation.getCurrentPosition() into initialize function to fix race where geolocation completes before map is co
nstructed.
New functions displayRegionOverlay() and removeRegionOverlay() to manage display of the region overlays.
Fixed issues where spinner doesn't get shut off.