Rename and deprecate filter module to prevent shadowing of built-in keyword

viewer_examples/plugins/canny_simple.py

@@ -1,5 +1,5 @@
 from skimage import data
-from skimage.filter import canny
+from skimage.filters import canny
 
 from skimage.viewer import ImageViewer
 from skimage.viewer.widgets import Slider

viewer_examples/plugins/collection_plugin.py

@@ -8,7 +8,7 @@ Demo of a CollectionViewer for viewing collections of images with the
 
 """
 from skimage import data
-from skimage.filter import rank
+from skimage.filters import rank
 from skimage.morphology import disk
 
 from skimage.viewer import CollectionViewer

viewer_examples/plugins/median_filter.py

@@ -1,5 +1,5 @@
 from skimage import data
-from skimage.filter.rank import median
+from skimage.filters.rank import median
 from skimage.morphology import disk
 
 from skimage.viewer import ImageViewer

viewer_examples/plugins/watershed_demo.py

@@ -1,7 +1,7 @@
 import matplotlib.pyplot as plt
 
 from skimage import data
-from skimage import filter
+from skimage import filters
 from skimage import morphology
 from skimage.viewer import ImageViewer
 from skimage.viewer.widgets import history