Added methods to read and write PLY-Format

~CHANGE: removed dependencies from GUI in TEST-Mode.
Merge branch 'fastkdtree-SS13-group1' of https://github.com/happah-graphics/happah into fastkdtree
Added code for Ray Generation as PointCloud

+Fix: Type FastKdTree in DefaultGUIManager.cpp
~Change: Removed deletion of iterators.