Pull One Ridge Continuous Wavelet Transform
ridge = ExtractRidge(ridgenum,wt,skellist,skelptr,skellen)
index of ridge to extract, 1 <= ridgenum <= nchains
continuous wavelet transform output by CWT
storage for list of chains
vector of length nchain -- pointers to heads of chains
len by 2 array of numbers, each row is a scale, amplitude pair
The amplitude of the wavelet transform is followed along the ridge chain.