initial github checkin
added submodules util, signals, pipeline, imageprocessing, gui
adjusted CMakeLists for submodules
adjusted includes (pipeline.h => pipeline/all.h)
adjusted include path for exceptions.h
updated util
added README
ImageStackHdf5Reader: removed debug hack
updated README
updated util
updated gui
implemented kd-tree search for candidate slices in segment extraction
implemented extraction of BranchSegments
implemented SegmentRandomForestEvaluator
updated util
sopnet.cpp: set threshold distance to a more useful default, added visualization command line options
fixed GroundTruthSegmentExtractor: didn't handle multiple slices of same neuron

Now, all possible segments between slices of the same label are enumerated and
accepted greedily based on the set difference ratio.
removed obsolete include
made segment features cachable, implemented caching for geometry features
updated pipeline