[mfcc] get_scale/power return smpl_t
[mfcc] validate input parameters, safer delete
[mfcc] remove plain dct ifdefs
[mfcc] default to full range when not using 40 filters
[mfcc] add slaney mode takes no params
[mfcc] remove note about power, add scale
[mfcc] add slaney (default) and documentation
[mfcc] add set_mel_coeffs and power
src/spectral/mfcc.c: avoid undef, use slow version if HAVE_NOOPT
src/spectral/mfcc.c: move declaration up
src/spectral/mfcc.c: use dct to compute mfcc
src/spectral/mfcc.c: fix typo
src/spectral/mfcc.c: clean-up trailing ;
src/spectral/: add const qualifiers
src/spectral/mfcc.c: use fmat_vecmul
src/spectral/mfcc.c: swap dct_coeffs matrix to prepare for fmat_vecmul
src/spectral/mfcc.c: improve build with -Wdeclaration-after-statement
src/fmat.c: new_fmat() takes height as first argument
src/spectral/mfcc.c: also delete dct_coeffs, thanks to SaBer, closes: #12
src/spectral: switch to mono