Remove the word unknown from the block 1 display.
Add the method doXPAFFT() which puts data from the XPA and XPA2 modules
through a Blackman filter.
Make various improvements to the XPA2 code to speed it up and generally
improve it.
Make the method doXPAFFT() private and have it called by the
symbolFreq() method which is called by the XPA and XPA2 classes.
Have the XPA2 method call the symbolFreq() method in the MFSK class so
that frequencies are measured more accurately.
Speed up the XPA code by only testing for sync and start up tones every
100 samples. Also put the XPA data through a Blackman filter to improve
measurement accuracy.
Update the README file.