Update (figured bass): V7 re-route

Re-route root position V7's to my :method:`resolveGeneralSeventhChord()'.

At of this update, other inversions (6/5, 4/3, 4/2) are still going through the original :method:`resolveDominantSeventhSegment()'.

Also added (7,3) as a shorthand for a seventh chord (7,5,3). This was not possible earlier because the :method:`resolveDominantSeventhSegment()' fails to handle complete root position V7 chords.