Update chord symbol style defaults
I propose updating the default styles for chord symbols as follows:
1) change user-visible names of text styles from "Chord Symbol A" and "Chord Symbol B" to "Chord Symbol" and "Chord Symbol (Alternate)"
2) change default alignment of chord symbols back to left aligned as per 2.x (perhaps update guitar templates to use center, as this makes sense when using fretboard diagrams)
3) change the "B" style to be same size as "A", italic, and above "A" (update jazz templates to make them consistent with this)