Fix HarmonicPeaks detection. Closes #56.

Output vectors of maxHarmonics size containing all harmonics, with
zero magnitudes representing ideal harmonics that were not found
among peaks. Before, only found harmonics were output, which could
have lead to incorrect behavior of Tristimulus and
OddToEvenHarmnonicEnergy algorithms.

Search for f0 only within the allowed deviation range around pitch,
output empty vectors otherwise.
Update docs for HarmonicPeaks to explain the new output format (#56).
Do not estimate f0 from spectral peaks, use the input pitch value

Current implementation of HarmonicPeaks will fail in the case of
missing f0. Do not estimate f0 as the closest peak to the input
pitch. Use the input pitch value directly, this will improve accuracy.
Merge branch 'harmonicpeaks_fix'