Remove thresholding subpackage and integrate into filter subpackage.

skimage/filter/__init__.py

@@ -4,3 +4,4 @@ from canny import canny
 from edges import sobel, hsobel, vsobel, hprewitt, vprewitt, prewitt
 from tv_denoise import tv_denoise
 from rank_order import rank_order
+from thresholding import threshold_otsu

skimage/filter/tests/test_thresholding.py

@@ -2,7 +2,7 @@ import numpy as np
 
 import skimage
 from skimage import data
-from skimage.thresholding import threshold_otsu
+from skimage.filter.thresholding import threshold_otsu
 
 
 class TestSimpleImage():

skimage/thresholding/__init__.py

@@ -1,2 +0,0 @@
-from .thresholding import threshold_otsu
-