[hpsdr] large FFT code added to Metis-enabled PowerSDR code

[w3sz]

I added my code for large FFTs [up to 262144] to Bill KD5TFD's 
Metis-enabled PowerSDR code.
I reworked my code a little bit while adding it to the new PowerSDR.  
Other than the obvious fact that this code works with Metis, the major 
visible improvements from my old code are:

1.  can now change FFT size on the fly with no problems
2.  code now maintains constant level for noise floor when changing FFT 
sizes
3.  3 waterfall palettes now available: standard, Linrad, and 
auto-leveling Linrad

There is also some cleaning up of my old code 'under the hood'.

The code [both source and binaries] is at:

http://www.nitehawk.com/w3sz/HPSDR-PowerSDR-Metis-W3SZ.zip

The zipped file is large, approx 98.5 MB

Enjoy!

-- 
73,

W3SZ
Roger Rehr
http://www.nitehawk.com/w3sz