fix member initialization and reporting in array caches
reference a github ilastik bug for a deadlock
import OpReorderAxis into lazyflow.operators
cross validation and other changes
init pmaps to 1 channel, assert the right channel index in setupOutputs
OpDenseLabelArray: Propagate NonzeroBlocks dirty state in propagateDirty(), not setupOutputs().
Fixes ilastik-475
OpReorderAxes: Ensure that upstream requests provide a plain numpy.ndarray view as the 'write into' but, not a vigra.VigraArray view, which can be troublesome for some operators.
OpH5WriterBigDataset: Write the data in the axis order of the original dataset, as provided by the original_axistags meta info.
wip