Create FFT.java

1) Synchronization with ReadAudioData thread works now - see synchronized (rlock) section
2) This thread is written periodically in while(true) cycle waiting for rlock to be released by ReadAudioData thread
3) FFT is applied to couple of blade: realOut and imagOut are now 2-dimensional arrays (not 1 dimensional) containing FFT results for 2 audio channels read from stereo WAV-file
static double[] [] realOut = new double[2] [iDatalength];
static double[] [] imagOut = new double[2] [iDatalength];