UI improvments
- added new camera scrolling function. Left mousebutton+ drag.
- centre camera target now by the middle mousebutton.
- changed "centre camera button" function.
- chancel a creation now just by right mousebutton.
- zoom is now right and left mousebutton instead of first right and then left.
- smooth change between different the camera movements.
- added the new controls to all tutorials, context based help, tooltips and menu.

Sorted and optimized "Beginner" campaign to get a constant progress and get into constructions more soon.
- sorted out 2 levels from the "Beginner" into the new "More" campaign.
- 2 new levels in "Beginner" campaign. Level 2+ Level 4

optimized Tutorial 1 to be easier, shorter and bigger. After finishing the level you can go on driving the old track as well.

the stress display in testmode keeps active now when changing to editor and return back to testmode.

- fixed some bugs