[FEA] Update API for consistency with upcoming scikit-image 0.19

[grlee77]

New functions introduced in 0.19 that are easy to port to cuCIM (via CuPy)

scikit-image/scikit-image#5158: Add normalized mutual information metric
scikit-image/scikit-image#5308: New illuminants were added to the color conversions
scikit-image/scikit-image#5382: Added ND butterworth filter
scikit-image/scikit-image#5420: Add no-reference perceptual blur metric.

Other easy functions are skimage.feature.blob_dog and skimage.feature.blob_log. Those two existed in v0.18, but had either bug fixes and/or a new argument added in v0.19.

channel_axis support:

scikit-image 0.19 adds a channel_axis argument that should now be used instead of the multichannel boolean. In scikit-image 1.0, the multichannel argument will likely be removed. We should start supporting channel_axis in cuCIM. Corresponding upstream PRs are:

scikit-image/scikit-image#5228: Decorators for helping with the multichannel->channel_axis transition
scikit-image/scikit-image#5284: multichannel to channel_axis (1 of 6): features and draw
scikit-image/scikit-image#5285: multichannel to channel_axis (2 of 6): transform functions
scikit-image/scikit-image#5286: multichannel to channel_axis (3 of 6): filters
scikit-image/scikit-image#5287: multichannel to channel_axis (4 of 6): metrics and measure
scikit-image/scikit-image#5288: multichannel to channel_axis (5 of 6): restoration
scikit-image/scikit-image#5289: multichannel to channel_axis (6 of 6): segmentation
scikit-image/scikit-image#5462: Add a channel_axis argument to functions in the skimage.color module
scikit-image/scikit-image#5427: residual multichannel->channel_axis fixes
scikit-image/scikit-image#5348: channel_as_last_axis decorator fix

Single-precision support

We did much of this already, but need to review for consistency with upstream now that it has been implemented there. Also, can expand the test cases using parameterization over dtypes as was done upstream.

scikit-image/scikit-image#4880: Richardson-Lucy deconvolution: allow single-precision computation
scikit-image/scikit-image#5200: Add float32 support to moments_hu
scikit-image/scikit-image#5204: single precision support in skimage.registration
scikit-image/scikit-image#5219: single precision support in skimage.restoration
scikit-image/scikit-image#5220: single precision support in skimage.metrics
scikit-image/scikit-image#5344: single precision support in moments functions
scikit-image/scikit-image#5353: single precision support in skimage.features
scikit-image/scikit-image#5354: single precision support in skimage.filters
scikit-image/scikit-image#5372: improved single precision support in skimage.transform
scikit-image/scikit-image#5373: single precision support in skimage.segmentation
scikit-image/scikit-image#5443: support single precision in skimage.color

API/Deprecations

• The selem argument has been renamed to footprint throughout the library. The footprint argument is now deprecated. (rename selem to footprint everywhere scikit-image/scikit-image#5445)
• Deprecate in_place in favor of the use of an explicit out argument in skimage.morphology.remove_small_objects, skimage.morphology.remove_small_holes and skimage.segmentation.clear_border
• The input argument of skimage.measure.label has been renamed label_image. The old name is deprecated.
• standardize on num_iter for paramters describing the number of iterations and max_num_iter for parameters specifying an iteration limit.
• The names of several parameters in skimage.measure.regionprops have been updated so that properties are better grouped by the first word(s) of the name. The old names will continue to work for backwards compatibility.
• In measure.label, the deprecated neighbors parameter has been removed (use connectivity instead).
• The deprecated skimage.color.rgb2grey and skimage.color.grey2rgb functions have been removed (use skimage.color.rgb2gray and skimage.color.gray2rgb instead).
• skimage.color.rgb2gray no longer allows grayscale or RGBA inputs.
• The deprecated alpha parameter of skimage.color.gray2rgb has now been removed. Use skimage.color.gray2rgba for conversion to RGBA.
• Attempting to warp a boolean image with order > 0 now raises a ValueError.
• When warping or rescaling boolean images, setting anti-aliasing=True will raise a ValueError.
• The bg_label parameter of skimage.color.label2rgb is now 0.
• The deprecated skimage.feature.register_translation function has been removed (use skimage.registration.phase_cross_correlation instead).
• The deprecated skimage.feature.masked_register_translation function has been removed (use skimage.registration.phase_cross_correlation instead).
• The default mode in skimage.filters.hessian is now 'reflect'.
• The default boundary mode in skimage.filters.sato is now 'reflect'.

Bug fixes

• Input labels argument renumbering in skimage.feature.peak_local_max is avoided (feature.peak_local_max changes labels scikit-image/scikit-image#5047).
• Nonzero values at the image edge are no longer incorrectly marked as a boundary when using find_bounaries with mode='subpixel' (Do not mark image edges in 'subpixel' mode of find_boundaries scikit-image/scikit-image#5447).
• Fix return dtype of _label2rgb_avg function.
• Ensure skimage.color.separate_stains does not return negative values.
• Handle 1D arrays properly in skimage.filters.gaussian.
• Fix Laplacian matrix size bug in skimage.segmentation.random_walker.
• Regionprops table (skimage.measure.regionprops_table) dtype bugfix.
• Fix skimage.transform.rescale when using a small scale factor.
• Fix multichannel intensity_image extra_properties in regionprops.
• Fix error message for skimage.metric.structural_similarity when image is too small.
• Do not mark image edges in 'subpixel' mode of skimage.segmentation.find_boundaries.
• Fix behavior of skimage.exposure.is_low_contrast for boolean inputs.
• Fix wrong syntax for the string argument of ValueError in skimage.metric.structural_similarity .
• Fixed NaN issue in skimage.filters.threshold_otsu.
• Fix skimage.feature.blob_dog docstring example and normalization.
• Fix uint8 overflow in skimage.exposure.adjust_gamma.
• Fix broken doctests in skimage.exposure.histogram and skimage.measure.regionprops_table. (fix histogram and regionprops_table doctests scikit-image/scikit-image#5522)
• Corrected phase correlation in skimage.register.phase_cross_correlation. (Fix computation of the correlation in register.phase_cross_correlation scikit-image/scikit-image#5461)