tests/nanshe/testOpColorizeLabelImage.py: Created a stub for testing operators from opColorizeLabelImage.
ilastik/applets/nanshe/opMaxProjection.py: Make sure the axis in question exists.
ilastik/applets/nanshe/opMeanProjection.py: Make sure the axis in question exists.
ilastik/applets/nanshe/opColorizeLabelImage.py: Enforce dataset constraints in OpColorizeLabelImage.
ilastik/applets/nanshe/opColorizeLabelImage.py: Added the operator OpColorizeLabelImageCached, which is cached version of OpColorizeLabelImage.
tests/nanshe/testOpColorizeLabelImage.py: Added a test for OpColorizeLabelImage.
tests/nanshe/testOpColorizeLabelImage.py: Added a test for OpColorizeLabelImageCached.