Include Classification and Segmentation Heads

• INTERFACE BREAK: rename attributes for feature and coordinate normalization
• add implementation for classification head
• add implementation for feature propagation module
• add implementation for segmentation head
• properly propagate training and mask tensors through the modules
• enable usage of different feature normalization layers
• add option to remove dropout layers
• some bugfixes
• update docstrings and readme

v0.1

Initial commit