memd_emd:
    added options 'localEMDparam', 'maxsift'.
    removed useless variable <aux>.
added memd_doNothingPost (test func for 'postprocess' option)
added memd_doNothingPre (test func for 'preprocess' option)
added memd_nonegfreq (a Quixotic attempt)
added memd_smoothBinSeries (utility function to help in writing weighting
    functions for 'localEMDfunc' option)
added memd_sumdumw (test func for 'localEMDfunc' option)