Function convert 

pub fn convert(wav: &Wav) -> ConvertedIr

Convert an IR exactly as the official app does (docs/05):

1. unless the file is a 48 kHz mono 24-bit WAV, convert it to one: the first channel, resampled with JUCE’s ResamplingAudioSource (resample_like_app), stored as 24-bit;
2. take the first IR_TAPS samples (zero-padded), time-reversed;
3. scale by app_gain.