Improve OCPNRegion performance.
Improve S57 Attribute management performance.
Refactor to improve S52 LUP/Lookup performance.
Improve S57 overlay cell logic performance
Improve S52 PLIB Lookup matching performance.
Implement configurable Route Arrival Circle Radius.
Improve Route waypoint arrival criterion logic.
Correct depth unit for BSB charts with UN=Meter (FS#1061)