Function classifySpelledInterval

classifySpelledInterval(
interval: SpelledInterval,
twoVoice?: boolean,
): ConsonanceClass
Classify a spelled interval by consonance, the way a counterpoint exercise reads it.

The spelling decides, not the semitone count: a diminished fourth is a dissonance though it sounds like a major third, and an augmented fifth is a dissonance though it sounds like a minor sixth. Only the perfect unison, fifth and octave and the major and minor thirds and sixths are consonant. The perfect fourth is context-dependent exactly as in classifyInterval.
Parameters
- interval: SpelledInterval
  The spelled interval between the two voices.
- twoVoice: boolean = true
  When true, the perfect fourth counts as a dissonance.
Returns ConsonanceClass
The counterpoint quality of the interval.
Example
```
import { classifySpelledInterval, ConsonanceClass, parseInterval } from '@libraz/libcantus';
classifySpelledInterval(parseInterval('d4')); // ConsonanceClass.Dissonance
classifySpelledInterval(parseInterval('M3')); // ConsonanceClass.ImperfectConsonance
```
- Defined in src/theory/counterpoint/internal.ts:69