Allow changing the max level through the UI

[stof]

Currently, the max level of the DIC visualizer is hardcoded in the JS code. It would be great to be able to change in through the UI.

[schmittjoh]

I have pushed the classes necessary to build the Javascript here:
https://github.com/schmittjoh/commons.js

Feel free to make adjustments, but I don't have much time for this bundle atm.