EqualTemperamentTuning = function(pitchesPerOctave) {
    var semitones = [];
    for (var i = 0; i < pitchesPerOctave; i++) {
        semitones.push(i);
    }
    Tuning.call(this, semitones, 2);
}
Equal temperament tuning.

@constructor
@extends Tuning
@param {Number} pitchesPerOctave The number of notes in each octave.