[idvusers] Map overlays

[Ben Kamen <bkamen@xxxxxxxxxxxxx>]

I remember IDV having U.S. Topo Maps in the catalogs of selectable
backgrounds for IDV... and I can't seem to remember where I saw it.

I know NCDC has it - but I'm trying to stick with IDV for the purpose
of what I'm working on.

Am I crazy?

-Ben