made NeuronsImageWriter create the output directory if not present
made slice overlap comparison to threshold value faster
added dependency to boost-timer
bugfix: input set callback in SliceExtractor was not called
updated gui
switched to templatized Slider implementation

Conflicts:

	modules/gui
	sopnet.cpp
bugfix: directory slice reader was not ignoring files
bugfix: made Segments return emtpy collection on section out-of-bounds
updated gui
set costs for end segments leaving the block to zero
added program option to disable the extraction of branches
greatly reduced Msers memory footprint

⇒ intermediate data structures are deallocated after the component tree has
  been built
greatly reduced memory footprint of Slice's distance maps

⇒ distance maps are now computed where needed -- in the Distance functor -- and
  regularly released by the process nodes that are asking for the distance values
updated util (can include config files now -- hooray! :) )
fixed output of SegmentExtractor for disabled branches
moved program option numTrees to module sopnet.training
made grid search a process node
implemented variation of information error measure
cleaned SegmentExtractor
replaced distance threshold for segment selection with overlap check