Show a list of annotations in addition to showing them on the score

[alastair]

It'd be nice to show a list of all annotations for a work rather than having to look on the score and click a box before seeing the contents of the annotation.

This could be a list of annotations on the left hand side, including information about the bar that the annotation is in (we'd have to find the elements that are in the annotation target and then count the bars in the score to determine this)

Clicking an annotation should highlight it on the score. Clicking an annotation that isn't on this page should flip the score to that page.