OpCompressedUserLabelArray: Added ingestData() for importing label values from an external slot in a block-by-block manner.
See also: ilastik/ilastik#167
classifiers: Added feature_count to the classifier ABC.
docs: Added classifiers docs
docs: Minor cleanups.
roi.py: Added slicing_to_string()
OpCompressedUserLabelArray: Added Projection2D slot (needs optimization)
OpCompressedUserLabelArray: Vastly improved performance by ignoring missing blocks.
OpCompressedArray: Projection2D colors are inverted so that objects in low-numbered slices occlude objects in high-numbered slices.
memory management: Use .total - .wired on Mac/Linux.
See #699
fix: psutil.virutual_mem().wired not available on linux
OpArrayCache: Fixed implementation of CleanBlocks output slot.
OpConcatenatedFeatureMatrices: Don't assert during setup. (If multiple images are changing their metadata at once, the assertion was firing in the middle of the change.)
Merge branch 'master' of ssh://github.com/ilastik/lazyflow
brief: modified exportDialog
Revert "brief: modified exportDialog"

This reverts commit 73dad10db49e40e34cdcdf3ed7b48dd895f86a67.
brief: modified exportDialog
brief: exporting raw/labels works (normalized/margin)