New: support for detecting 5-4-4-3 fake suspensions in dissonance.py

Fake suspension that create the interval pattern 5-4-4-3 are also detected
now. Previously only 3-4-4-3 fake suspensions were detected.
Fixed: reverts to nan labels for consonant fourths and fifths in dissonance.py

Having a flexible labelling method was problematic at the stage of the
ConsMakerIndexer so the labels for consonant fourths and fifths was changed
back to just nan.
Formatting: comments out special fourths code in dissonance.py

This is because there is now a dedicated indexer that examines fourths and
fifths and labels them consonant if appropriate.
Formatting: simplified passing_ind_func code in dissonance.py

Replaced hard-coded comparisons with a more generalized approach to discerning
passing tones eliminating 55 lines of code.
Formatting: further simplified passing_ind_func in dissonance.py

Eliminated some superfluous lines of code.
Formatting: simplified code in neighbour_ind_func in dissonance.py

Simplified logic that identifies neighbour tones.
Formatting: modularized cons_maker_ind_func in dissonance.py

Made code easier to read and fixed some bugs.
New: detection of nota cambiatas in dissonance.py

To achieve this the NotaCambiataIndexer was created. Other minor bug fixes
in dissonance.py too.