Exception thrown when creating an AOI with a pourpoint where the basinarea field is null

[lbross]

BAGIS V3 tries to convert this value to a double for use within the application and crashes ArcMap. If we handle this and treat it as a 0, BAGIS V3 sets the reference area to 0.00 or 'Not specified' in succeeding steps. Let me know if this is OK.

[jdduh]

Refer to PSU-CSAR/awdb-retrieve#5 for the spec of the future source of the gauge stations data.

[lbross]

Do we need to make additional changes to BAGIS v3 if the basinarea will not be available going forward? When I search for that global variable I find that it's used in 4 or 5 places in messageBoxes and/or UIs. The application appears to handle its absence gracefully, but do we want to leave these fields in the UI when they will always be null or undefined? If we decide to excise it, I'll do a deeper dive to see exactly where/how it's used.

[jdduh]

BAGIS V3 users have the option to create new AOIs from arbitrary locations. In these cases, BAGIS can handle the process without needing the information in basinarea. We can just leave the UI alone in case awdb starts to populate AOI areas in the future.