Moving through the Graph elements in the Application element should both play and provide context to the screen reader

[frastlin]

Currently, when you hit enter on the application element, you can arrow through points on the graph. The screen reader says:
"x, 0, 0. Sensor Data (Y value). graphic"
There are a couple issues with this:

1. There's no contextual information saying how many elements there are and what element you are on. I would like to add something like:
   "x, 0, 0. Sensor Data (Y value). 1 of 175"
2. Get rid of the "graphic" piece.
3. Arrowing through should play the pitch associated with the value you are on.
4. Pressing "p" should play and pause the playback from where you are, and when you pause the playback, you should jump to the element you're hearing.
5. If you hold down arrow keys, it should play an understandable version of the graph audio.
6. Pressing up and down arrows should move you between series.
7. Pressing space should solo the series and select it.

These features would really improve the experience.