(documentation) synchronize version to future friture version
Comment the frames_per_buffer issue in pyaudio
(git) Do not track files in build and dist directories
(git) Ignore files in doc/_build
Major improvement of the spectrogram

Now properly samples the time-frequency space (hamming window, 75%
overlap), followed by linear interpolation on the time and frequency
axes.

The custom timer with varying period is completely removed, which
results in a much improved fidelity of the time scale, as can be
seen on the spectrogram of a sweep signal, and also allow to reach
very small time scales: 0.1s is possible without Xruns, whereas I
could not go below 10s on my machine with the previous code (Win7-
Atom N540).

For speed, several changes have also been made:
- the colormap code is implemented in Cython
- the new online linear interpolation in time is implemented in
Cython
- the fft module (audioproc) no longer computes the sqrt of the PSD,
since we do a log anyway afterwards, where the sqrt boils down to a
multiplication factor (also affects the FFT spectrum widget)
- the drawing of data to the screen pixmap is done all-at-once
instead of one data column at a time. This dramatically reduces
the time spent in QPainter.drawImage.
(audioproc) implement the complex norm square in Cython
(sandbox) unfinished implementation of a sinc online resampler
(spectrogram) Note that implementing log10 in Cython is not faster
(fir/iir sandbox) Fix import paths, add timing info
Add sandbox file for overlap-add fir filtering
New file for testing the ringbuffer
New file for testing the subsampler
Factorize growing code in ringbuffer
Cleanup code for audiobuffer filling
Fix chunks count when input overflows
Add windowing to delay estimation fft, and fix G zero-avoidance
Add testing for empty push in ringbuffer test code
Fix subsampler issue on empty array
Fix multiple ringbuffer growth by growing larger in prevision
Fix handling of buffer offset reset in spectrogram