dataLoaded -> loaded. Program.fromUserJSON. Reduce debug output.

* Event 'dataLoaded' becomes 'loaded'.
* Introduce Program.fromUserJSON.
* Reduce output.
Bring padding-left of .turingmachine into account.
Major refactoring for AnimatedTuringMachine. General development.

- Introduce Queue.
- Program was simplified. Because hashing was one-directional,
  import/export was broken. We restrict symbols to string values.
  Testcases adapted. Drop toUserJSON/fromUserJSON.
- Introduce stepFinished event.
- GearVisualization also implements event handling now.
- updateTapeToolTip became UI function.