Add wrappers for imagecorruptions library

This patch adds wrappers around the functions from
package
https://github.com/bethgelab/imagecorruptions.
The functions in that package were used in some recent
papers and are added here for convenience.
The wrappers produce arrays containing values
identical to the output arrays from the corresponding
`imagecorruptions` functions when called via the
`imagecorruptions.corrupt()` (verified via unittests).
The interfaces of the wrapper functions are identical to the
`imagecorruptions` functions, with the only difference of
also supporting `seed` parameters.

* Add module `imgaug.augmenters.imgcorruptlike`.
  The `like` signals that the augmentation functions do
  not *have* to wrap `imagecorruptions` internally.
  They merely have to produce the same outputs.
* Add the following functions to module
  `imgaug.augmenters.imgcorruptlike`:
    * `apply_gaussian_noise()`
    * `apply_shot_noise()`
    * `apply_impulse_noise()`
    * `apply_speckle_noise()`
    * `apply_gaussian_blur()`
    * `apply_glass_blur()`
      (improved performance over original function)
    * `apply_defocus_blur()`
    * `apply_motion_blur()`
    * `apply_zoom_blur()`
    * `apply_fog()`
    * `apply_snow()`
    * `apply_spatter()`
    * `apply_contrast()`
    * `apply_brightness()`
    * `apply_saturate()`
    * `apply_jpeg_compression()`
    * `apply_pixelate()`
    * `apply_elastic_transform()`
* Add function
  `imgaug.augmenters.imgcorruptlike.get_corruption_names(subset)`.
  Similar to `imagecorruptions.get_corruption_names(subset)`,
  but returns a tuple
  `(list of corruption method names,
    list of corruption method functions)`,
  instead of only the names.
* Add the following augmenters to module
  `imgaug.augmenters.imgcorruptlike`:
    * `GaussianNoise`
    * `ShotNoise`
    * `ImpulseNoise`
    * `SpeckleNoise`
    * `GaussianBlur`
    * `GlassBlur`
    * `DefocusBlur`
    * `MotionBlur`
    * `ZoomBlur`
    * `Fog`
    * `Frost`
    * `Snow`
    * `Spatter`
    * `Contrast`
    * `Brightness`
    * `Saturate`
    * `JpegCompression`
    * `Pixelate`
    * `ElasticTransform`
* Add context `imgaug.random.temporary_numpy_seed()`.

changelogs/master/added/20191218_imagecorruptions.md

@@ -0,0 +1,62 @@
+# Added Wrappers for `imagecorruptions` Package #530
+
+Added wrappers around the functions from package
+[bethgelab/imagecorruptions](https://github.com/bethgelab/imagecorruptions).
+The functions in that package were used in some recent papers and are added
+here for convenience.
+The wrappers produce arrays containing values identical to the output
+arrays from the corresponding `imagecorruptions` functions when called
+via the `imagecorruptions.corrupt()` (verified via unittests).
+The interfaces of the wrapper functions are identical to the
+`imagecorruptions` functions, with the only difference of also supporting
+`seed` parameters.
+
+* Added module `imgaug.augmenters.imgcorruptlike`. The `like` signals that
+  the augmentation functions do not *have* to wrap `imagecorruptions`
+  internally. They merely have to produce the same outputs.
+* Added the following functions to module `imgaug.augmenters.imgcorruptlike`:
+    * `apply_gaussian_noise()`
+    * `apply_shot_noise()`
+    * `apply_impulse_noise()`
+    * `apply_speckle_noise()`
+    * `apply_gaussian_blur()`
+    * `apply_glass_blur()` (improved performance over original function)
+    * `apply_defocus_blur()`
+    * `apply_motion_blur()`
+    * `apply_zoom_blur()`
+    * `apply_fog()`
+    * `apply_snow()`
+    * `apply_spatter()`
+    * `apply_contrast()`
+    * `apply_brightness()`
+    * `apply_saturate()`
+    * `apply_jpeg_compression()`
+    * `apply_pixelate()`
+    * `apply_elastic_transform()`
+* Added function
+  `imgaug.augmenters.imgcorruptlike.get_corruption_names(subset)`.
+  Similar to `imagecorruptions.get_corruption_names(subset)`, but returns a
+  tuple
+  `(list of corruption method names, list of corruption method functions)`,
+  instead of only the names.
+* Added the following augmenters to module `imgaug.augmenters.imgcorruptlike`:
+    * `GaussianNoise`
+    * `ShotNoise`
+    * `ImpulseNoise`
+    * `SpeckleNoise`
+    * `GaussianBlur`
+    * `GlassBlur`
+    * `DefocusBlur`
+    * `MotionBlur`
+    * `ZoomBlur`
+    * `Fog`
+    * `Frost`
+    * `Snow`
+    * `Spatter`
+    * `Contrast`
+    * `Brightness`
+    * `Saturate`
+    * `JpegCompression`
+    * `Pixelate`
+    * `ElasticTransform`
+* Added context `imgaug.random.temporary_numpy_seed()`.

imgaug/augmenters/__init__.py

@@ -12,6 +12,7 @@
 from imgaug.augmenters.edges import *
 from imgaug.augmenters.flip import *
 from imgaug.augmenters.geometric import *
+import imgaug.augmenters.imgcorruptlike  # use as iaa.imgcorrupt.<Augmenter>
 from imgaug.augmenters.meta import *
 import imgaug.augmenters.pillike  # use via: iaa.pillike.*
 from imgaug.augmenters.pooling import *