sopnet.cpp: don't compile HDF5 stuff, if we don't have it
bugfix: uninitialized sizes in NeuronsStackView and SplitMergePainter
rewrote GroundTruthExtractor to create minimal spanning trees on candidate continuations
made binary problemdump aware of HAVE_HDF5
bugfix: GroundTruthExtractor did not get best next edge
new SliceExtractor constructor: turn on/off downsampling of component tree
fixed slice offset in visualization
splitmerge: added option to start from scratch
started implementing SliceEditor for SplitMerge
finished implementation of SliceEditor
finished slice editing in SplitMerge
improved visualization of SliceEditor
bugfix: initial value of program option in GeometryFeatureExtractor was of wrong type
changed StackSliceExtractor to use conflict sets instead of linear constraints
bugfix: groundtruth was not set in Sopnet if training was disabled
updated gui
don't create empty synapse constraints
added getVariables() to ProblemConfiguration
added option to show neurons in 3D to splitmerge

This uses a temporary fix to solve the scope problem of nested process nodes.
This fix will not be needed later anymore when we merge the new pipeline version.
changed GroundTruthExtractor to prefer closer continuations when overlap is the same