gnu: python-scikit-image: Update to 0.14.1.

Also add explicit Python2 variants for its dependency closure.

* gnu/packages/python.scm (python-scikit-image): Update to 0.14.1.
[source](uri): Use PYPI-URI.
[propagated-inputs]: Add PYTHON-CLOUDPICKLE, PYTHON-DASK, PYTHON-MATPLOTLIB
and PYTHON-PYWAVELETS.
(python2-toolz, python2-cloudpickle, python2-locket, python2-blosc,
python2-partd, python2-dask): New public variables.

gnu/packages/python.scm

@@ -2822,25 +2822,26 @@ and is very extensible.")
 (define-public python-scikit-image
   (package
     (name "python-scikit-image")
-    (version "0.11.3")
+    (version "0.14.1")
     (source
      (origin
        (method url-fetch)
-       (uri (string-append
+       (uri (pypi-uri "scikit-image" version))
-             "https://pypi.python.org/packages/source/s/scikit-image/scikit-image-"
-             version ".tar.gz"))
        (sha256
-        (base32 "0jz416fqvpahqyffw8plmszzfj669w8wvf3y9clnr5lr6a7md3kn"))))
+        (base32 "0l1c3rl4s1jyv80i5hns4pgih09zrxfj7lygdc51w8sgyysb7ac6"))))
     (build-system python-build-system)
     (arguments
      ;; TODO: Some tests require running X11 server. Disable them?
      '(#:tests? #f))
     ;; See DEPENDS.txt for the list of build and run time requiremnts
     (propagated-inputs
-     `(("python-matplotlib" ,python-matplotlib)
+     `(("python-cloudpickle" ,python-cloudpickle)
+       ("python-dask" ,python-dask)
+       ("python-matplotlib" ,python-matplotlib)
        ("python-networkx" ,python-networkx)
-       ("python-scipy" ,python-scipy)
+       ("python-pillow" ,python-pillow)
-       ("python-pillow" ,python-pillow)))
+       ("python-pywavelets" ,python-pywavelets)
+       ("python-scipy" ,python-scipy)))
     (native-inputs
      `(("python-numpy" ,python-numpy)
        ("python-cython" ,python-cython)
@@ -14516,6 +14517,9 @@ library's @code{threading} module.")
 functions, and dictionaries.")
     (license license:bsd-3)))
 
+(define-public python2-toolz
+  (package-with-python2 python-toolz))
+
 (define-public python-cytoolz
   (package
     (name "python-cytoolz")
@@ -14598,6 +14602,9 @@ shipped over the network to execute on remote hosts, possibly close to the
 data.")
     (license license:bsd-3)))
 
+(define-public python2-cloudpickle
+  (package-with-python2 python-cloudpickle))
+
 (define-public python-locket
   (package
     (name "python-locket")
@@ -14617,6 +14624,9 @@ data.")
 they use the same path.")
     (license license:bsd-2)))
 
+(define-public python2-locket
+  (package-with-python2 python-locket))
+
 (define-public python-blosc
   (package
     (name "python-blosc")
@@ -14648,6 +14658,9 @@ regular-spaced values, etc.
 This Python package wraps the Blosc library.")
     (license license:bsd-3)))
 
+(define-public python2-blosc
+  (package-with-python2 python-blosc))
+
 (define-public python-partd
   (package
     (name "python-partd")
@@ -14673,6 +14686,9 @@ This Python package wraps the Blosc library.")
 append on old values.  Partd excels at shuffling operations.")
     (license license:bsd-3)))
 
+(define-public python2-partd
+  (package-with-python2 python-partd))
+
 (define-public python-dask
   (package
     (name "python-dask")
@@ -14727,6 +14743,9 @@ larger-than-memory or distributed environments.  These parallel collections
 run on top of the dynamic task schedulers. ")
     (license license:bsd-3)))
 
+(define-public python2-dask
+  (package-with-python2 python-dask))
+
 (define-public python-ilinkedlist
   (package
     (name "python-ilinkedlist")