Refactoring v1.0 prep

This is the first big refactoring step towards v1.0 Lots of functions changed places and names, so there are probably lots of bugs to correct now.

qim3d/processing/__init__.py

 from .local_thickness_ import local_thickness
 from .structure_tensor_ import structure_tensor
 from .detection import blob_detection
-from .filters import *
 from .operations import *
 from .cc import get_3d_cc
 from .layers2d import segment_layers, get_lines