Rotational symmetry modified wavelet compatibility

Pretty much a line-by-line copy of dtwavexfm2b() as it appears in the MATLAB toolbox. You may prefer to merge dtwavexfm2() and dtwavexfm2b() into one function which can handle the extra coefficients returned by qshift and biort. As it is, the use of 'qshift_b_bp' and 'near_sym_b_bp' (which I have included in .npz format) is pretty much hardcoded in dtwavexfm2b.