Various enhancements

1) Improved some comments
2) Better json check in api data conversion
3) Rearranged options in App
4) Added API options in App, in order to init right away
5) Recovered spliceLinksForNode function that was wrongfully removed
6) Moved some of the event logic to App.behavior
7) Better handling of edge case in Toolbar resizing
8) Renamed App.layout.restart to App.layout.update
Rewrote events and connected to API (first version)

1) Transformed existing way for dragging connections to d3.drag behavior
2) Moved non-graphical parts of mouse-events to App.behavior
3) Connected the creation of lines and circles to the API
Altered the init of API to the init of App (new style)