Renamed ThreshWaveletCoeff to EncodedPreCompContrib in pmapcontrib.c, since only needed for encoding of wavelet coeffs. pmcontrib4.c:decodeContribs() decodes directly into the binnedContrib buffer (pending cache implementation), so no extra struct is infact needed there; another of many realisations after the fact, albeit a simplifying one in this case. This obviates expandContribs(), which has been removed. Debugging of contribution decoding still pending.