[aprssig] APRS Radiation sensor

[Bob Bruninga]

> Someone commented to me that we need an icon for a
> radiation monitor. 

Done.  See http://aprs.org/symbols/symbols-new.txt

The symbol is  "RH" where #H is the "hazards category" and "R" stands for
Radiation.  If there is any reason why this is not the best idea, lemme
know.  Otherwise, its done.

Parent page is www.aprs.org/symbols.html

Remember, now that the spec addendum1.2 supports overlays on ALL symbols, we
have room for these kinds of additions.  The problem is, no one will see
them until clients update their symbol tables.

Notice, that although this is an "H" symbol with an "R" overlay, there is
nothing prohibiting APRS clients from giving such combinations a unique
symbol of their own.  I can imagine a great "atom" carracture as a symbol...

Bob, Wb4APR