chromatic intervals

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I have a suggestion for the addition of chromatic intervals to 
mingus.core.intervals (to allow for chromaticism within a key):

Diminished intervals:
Diminished First (d1)   Negative one half step (ex. C to B)
Diminished Second (d2)  Zero half steps (the same note; ex. D to D)
Diminished Third (d3)   Two half steps (ex. G# to Bb)
Diminished Fourth (d4)  Four half steps (ex. C# to F)
Diminished Fifth (d5)   Six half steps (ex. D to Ab)
Diminished Sixth (d6)   Seven half steps (ex. C to Abb)
Diminished Seventh (d7) Nine half steps (ex. D to Cb)
Diminished Eighth (d8)  Eleven half steps (ex. C to Cb)

Augmented intervals:
Augmented First (A1)    One half steps (ex. C to C#)
Augmented Second (A2)   Three half steps (ex. F to G#)
Augmented Third (A3)    Five half steps (ex. E to Gx)
Augmented Fourth (A4)   Six half steps (ex. D to G#)
Augmented Fifth (A5)    Eight half steps (ex. C to G#)
Augmented Sixth (A6)    Ten half steps (ex. G to E#)
Augmented Seventh (A7)  Twelve half steps (ex. E to Dx)
Augmented Eighth (A8)   Thirteen half steps (ex. F to F#)

And, to be thorough, perhaps even:
If the octave is kept track of.
Perfect intervals:
Perfect Unison(P1)            Zero half (ex. C-4 to C-4)
Perfect Octave(P8)            Thirteen half steps (ex. C-4 to C-5)

If you are open to it, I'd very much like to contribute. I have a BM in music 
theory from SFSU and am in my final term studying computer science at CSU 
Chico. Since this is a fairly simple issue could I try to work on this for you? 
Thank you.

Original issue reported on code.google.com by OrtalisM...@gmail.com on 20 Feb 2013 at 7:53