Updated Charleston FPGA code

[Terry Fox]

In order to make sure that everyone is using the same/proper version of 
Charleston FPGA code, I have modified it to add a (approx) 1Hz blink to 
LD7, instead of that LED being always ON.  I renamed the resulting .bit 
file to: sdrif500kIQ_flash.bit. This indicates that the bit file is for 
a 500k Nexys2 board, with I/Q sequence corrected, and the LED flashes.  
The flashing makes it immediately obvious that the new version FPGA code 
is running.  Or at least if "immediately" is longer than about two seconds!

Once I have access to edit/change the AMRAD website again, I will upload 
it there, with big bold letters indicating it is the right version to 
use.  Until then, I can send the .bit file to anyone interested, it's 
only about 430k big.  Right now the AMRAD site is read-only, due to some 
server changes.

I have had the domain wb4jfi.com for a little while now, but have not 
attempted to edit it, or create anything meaningful there.  If I get 
some time, I will put a few various files there, including this one.  
I'm contemplating putting much of the Charleston files and information 
there as a backup to the AMRAD website.

Enjoy.
Terry
WB4JFI