src/pitch/pitchspecacf.c: set confidence to 0. for now
wscript: remove x86_64 for iosimulator
src/tempo/beattracking.c: do nothing if period is zero
wscript: also exclude zips
python/tests/run_all_tests: ignore more unstable
src/fmat.h: fmat_get_channel to write to an fvec_t
src/spectral/filterbank.h: improve documentation