Removed solidity from features, this was no longer being used and was triggering convex hull warnings

Implementing alternative dataframe generation where z-positions are in object map, i.e. do not need to be de-projected from raw

Implemented and tested object identity labeling in 3D with and without connectivity between z-frames

Cleared up issues with Singleton behavior, largely confused by the fact this python logger itself is a Singleton that persists between tests

Mocked up session logging implementation using python log service; two tests are failing apparently due to Session singleton-related issues

record entry returned by object class map export is no longer a dictionary of paths, but rather one path for object map

API test cases now call PUT through an internal method with re-attempts built in; trying to eliminate lost connections during testing but some still happen

Now that RoiSet is in base, remove dependency on ilastik in its test; tests now open segmentation mask from file