carving: When exporting meshes, just skip 'objects' that are empty and therefore have no meshes extracted.
Added option "--retrain" to headless mode of pixelClassificationWorkflow
PixelClassification: --retrain flag works even in non-headless mode.
ilastik.py: Use os.path.expanduser to eliminate '~' in --project or --new_project args.
Allow ilastik version to have letter suffixes like '1.0.5b'
Merge branch 'retrain-headless'
moved callback connections to end of __init__
Merge pull request #882 from burgerdev/issue-878

[ThresholdTwoLevelsGui] moved callback connections to end of __init__
Merge branch 'master' into thresholding-documentation
adjusted graph-cut unit tests to canonical axes order
adjusted OpGraphCut to canonical axes order
adjusted OpObjectsSegment to canonical axes order