Enhancement: up/down keys should navigate annotation list

[azaroth42]

In order to actually /read/ the transcription, you need to constantly click the annotation boxes, either on the canvas or in the list. It would be much easier if the annotation list were focused that up/down arrow keys navigated to the previous/next annotation.

[aeschylus]

Very much agreed. This has been in the back of my mind for awhile. In general I would find a number of keyboard shortcuts helpful. For instance, there is no way to tab through interface elements outside of a single widget's window. You also can't access global menus from the keyboard or control generally anything with the keyboard.