fixes #609
Merge pull request #107 from burgerdev/issue-609

fixes ilastik/ilastik#609
change the way axistags for stacks are created. now works on windows
remove a print statement
Merge branch 'master' of ssh://github.com/ilastik/lazyflow
RandomForest operators: Removed MaxLabel input slot:
- OpTrainRandomForestBlocked: Determine max label immediately after requesting labels.
- OpPredictRandomForestBlocked: Get max label from classifier.labelCount().
OpValueCache: Added fixAtCurrent slot.
OpTrainRandomForestBlocked: Removed fixClassifier slot.
If you want to freeze the classifier, use a cache with fixAtCurrent slot (e.g. OpValueCache).
OpTrainRandomForestBlocked: maxLabel is max across all label images, not just blocks within the last label image!
OpExportSlot: Connect progressSignal when exporting to multipage tiff.
OpPredictRandomForest: Re-added LabelsCount slot, which is necessary to determine the output shape without re-training the classifier during setupOutputs().
roi.py: Cleanups.
RequestPool: Use block() instead of wait(), since the request result is not returned.
(This allows clients to clean the request in the notify_finished() handler if desired.)
RoiRequestBatch: Use Request-aware SimpleRequestCondition as the synchronization object.
See also: ee60f29b81229589514ae29df44ee70ff819636e and 90ec486b7503c312efb24322fe619ef6febde420
OpTrainRandomForestBlocked: Re-added the MaxLabel slot.  Turns out to be necessary after all.
This essentially undoes commit 831ba02b1df50aa3110e452ad07f6bb2d4101676
Added OpBlockedLabelArray and test.
OpBlockedArray: Clip nonzero block rois to image shape.
Improved an assert message.
tests: testOpBlockedLabelArrary: Added a basic benchmark for label creation, deletion.
OpBlockedLabelArray: Removed maxLabel output.