The Rain radar, Lightning density and Satellite clouds rows named NOAA
nowCOAST until a manifest named its own source, whatever the source read.
A weather source may now supply sourceName(kind), kind being radar,
lightning or satellite; the row shows that name until a manifest names one.
The name is read once when the layer is built and held to the same rule as
a manifest's display.source. A source without names, or one whose name is
refused or fails, still shows NOAA nowCOAST.