wave: remove image size limits
interpolate samples per x-pixel
NOOP: move variable declarations to top of each scope
fix buffer allocation
update copyright year
waveform: allow to use audio-frames as x-unit
Whitespace fixes.
Makefile.am : 'make check' target depends on $(bin_PROGRAMS).
src/resample.c : Fix valgrind warning.
src/kaiser_window_test.c : Change result reporting.
src/waveform.c : Whitespace.
Add a valgrind test for some of the execuables.
Improve selection of FFT size to be the closest fast one

sndfile-spectrogram uses fftw_plan_r2r_1d() whose documentation says:
"FFTW is generally best at handling sizes of the form
    2^a 3^b 5^c 7^d 11^e 13^f
where e+f is either 0 or 1, and the other exponents are arbitrary."

Before, it just added 1-32 to the size to make it a multiple of 32,
which is both wrong for speed and always gives you a bigger FFT
than the one you asked for, even if the dimension is already perfect.

This gives the same or the closest valu that is also >= the graph's height.

The resulting speedup is, for 8192 height, a factor of two (62s -> 33s)
Reduce minimum spectrogram size to 1x1

It used to check for minimum 640x480. Now it works down to 1x1.
The border and legends get a bit crushed at tiny sizes, but hey.
Whitespace cleanup.
Scripts/cstyle.py : Updates.
doc/index.html : Fix typo. Thanks Arjen Lentz.
src/waveform.c : Fix channel test.
src/waveform.c : Make sure frames_per_buf doesn't get too big.

Fixes https://github.com/erikd/sndfile-tools/issues/11
src/waveform.c : Minor cleanup.