proposition of modifications for tutorial 2

Here are a few comments on the modifications I brought:
- The tutorial was using references to build the world. When I tried I ended up with a segfault. To solve simply the problem I passed to a pointer as in src. I think this is simply due to the fact that you can't point to a ref (http://stackoverflow.com/questions/4632528/what-does-class-cls-mean-in-cs-function-definition).
- The second parameter of registerDynamicRaster is not very well described. How does true lead to the results to be stored in results.h5 ?
- I have update the figures to show what I have on screen, maybe I missed a step that would explain the differences between my picutres and the ones that were there.