Multiply with a Kaiser window before taking FFT.
Do not track .pyc files.
Make several changes.

- Use the select module for non-blocking input. This is now used to stop
  the program.
- Separate the tuner from the script that executes it. This enables
  creation of a .pyc file for tuner.
- Use a certain range of frequencies within which to find the peak. This
  gives you only the harmonics of interest.
- Make plotting the time domain signal as well as the frequency spectrum
  optional via arguments to the function.
- Plotting is now object-oriented, so it is much faster (esp. line-
  removal)