addEndpoint method
Add an endpoint to the map, creating an entry for it if none exists
Implementation
void addEndpoint(Map endPoints, Coordinate p, bool isClosed) {
EndpointInfo eiInfo = endPoints[p] as EndpointInfo;
if (eiInfo == null) {
eiInfo = new EndpointInfo(p);
endPoints[p] = eiInfo;
}
eiInfo.addEndpoint(isClosed);
}