Jakob Miland

As the title says, we should support extended chords up to a thirteenth. As of now we only support sevenths.

Issue is described in #83 as well. Transposing chord `Amaj7/C#` a minor third should produce `Cmaj7/E` but right now it returns `Cmaj7/C#` which is clearly not correct. The problem is...

... apparently is an odd-case. I'll need to dig deeper into this, but right now it seems that we're doing it wrong, by basically just inverting the simple part of...