- partially switched to new logger module instead of prints
- resolved remaining py2-py3 incompatibilities with dictionaries

# Conflicts:
#	syconn/cnn/TrainData.py

- added tripletnet architecture

- minor server.py changes
- fixed mapping of axon predictions to CS / conn. objects

- py3 fix in 'chunkify' method

added glia GT and data class for CNN training (currently it is not possible to start this network architecture with python3 ...)

Dense segmentation

- added method to render label views to rendering.py
- general code refactoring

- minor fixes

- fixed rotation differences for index- vs. raw/-label views because different PCA results
- minor fixes