Hall Effect Bricklet

I added support for the Hall Effect Bricklet to BrickV. On the top of the graph should be the value of edge count but I couldn't figure out how to display the value of the Bricklet in the graph and show the edge count on the top of the graph. It's your turn ;) Currently the value is displayed in the graph as well as on the top.
![brickv-hall-effect](https://f.cloud.github.com/assets/3150817/2423904/c677affe-aba0-11e3-8491-a6ba37a78aba.JPG)