#41 Bugfixing, Revising Code : various things

- used Input Fields ( #26 ) for increasing/decreasing background
visibility
- fixed projection for #38 , #36 ,  by narrowing down what is drawn
- fixed various issues with wrong indexation of voxel grid ( #--> now
consistent across all shaders per worldToVoxel Matrix
- some refining of debug views and other input options
- generic Print Value Listener ( finally )