[idvusers] Displaying Locations in IDV

Hi Everyone,

A couple of issues with displaying custom locations, one possibly a bug:

1) When attempting to load a custom locations xml, as per
http://www.unidata.ucar.edu/software/idv/docs/userguide/data/LocationXml.html,
I have found it is necessary to manually specify the Data Source Type as
"Locations".  Ie. It will not load correctly if you follow the default,
"I'm feeling lucky".

2) In a Globe View, displayed locations disappear when zooming in beyond a
certain point, regardless of the vertical positioning of the locations.
Upon zooming out, past that same zoom point, the locations return.  This
does not happen in Map View which behaves as expected (the locations are
present on all zoom levels).

Paul