Kwimage

Added
* "torchvision" nms mode.
* Ported pure-image drawing functions from kwplot. These are `draw_boxes_on_image`, `draw_clf_on_image`,
`draw_text_on_image`, `make_heatmask`, `make_orimask`,
`make_vector_field`.
* Ported Color from kwplot


Fixed
* Using the new (correct) torch defaults for `align_corners` in `warp_tensor` when possible.
* Fixed bug in "numpy" nms mode.

Changed
* reworked nms auto mode
* nms impl=`cpu` / `gpu` / `py` are now deprecated for `cython_cpu` / `cython_gpu` / `numpy` instead.

Changed
* First public release

Added
* Add option (hack) to build without C-extensions

Added
* Add `imresize` as a more powerful alternative to `imscale`.
* The `imread` function now accepts a `backend` kwarg, which allows the user to control how an image is loaded.
* Add `clip` method to `Polygon`
* Add `class_idx` data-key to `Heatmap` for semantic segmentation support.
* Add `class_energy` data-key to `Heatmap` for non-probabilistic output support.
* Add `Detections.from_coco_annots`, to create detections from COCO-style annotations.
* Add `to_coco` methods to all structures.
* Add `meta` to `Polygons`

Changed
* `Coords.warp` now tentatively supports OSR transforms.
* Continue improvements of annotation structures
* Increased efficiency of Cython CPU non-max-suppression
* `imread` now read ptif and tiff files using GDAL by default
* `imread` now reads `.r0` images using GDAL.
* Tweaked implementation of `Heatmap.random`.
* `ensure_uint255` and `ensure_float01` now raise proper `ValueErrors` instead of using assert statements.
* `Points` draw methods now accept 'classes' as a color arg

Fixed
* `imread` can now handle nsf and color table images.
* Python2 issues with `Boxes.__repr__`
* Can now correctly draw 1D `Boxes` objects
* Python2 issues mask shape using List[long] instead of List[int]
* Zero division in Cython `non-maximum-supression` with zero sized boxes.
* `Heatmap.shape` now works even if `class_probs` is not set.
* `Coords.warp` now works with tensors.
* `Coords.warp` uses nearest neighbor interpolation for integer warping.

Issues
* Heatmap.warp may have some odd behavior and emit warnings.

Added
* Add `Detections.rasterize` method to which is a lossy "pseudo-inverse" of `Heatmap.detect`.
* All classes in `kwimage.structs` should now have warp and draw method
* Add `subpixel_setvalue` and `subpixel_getvalue`
* Add `Coords` data structure
* Add `Mask` data structure
* Add `Points` data structure
* Add `Polygon` data structure
* Add `_generic.ObjectList` data structure for `MaskList` and `PointsList`.
* Add `util_warp.warp_points`

Changed
* Speedup `overlay_alpha_layers` by bypassing redundant `np.dstack` operations.
* Changed `encode_run_length` to return a dictionary
* Add `output_shape` and `input_shape` as generally accepted kwargs for warp (even if they are unused)
* Spatial data structure `warp` methods can now accept `imgaug` augmenters
* Add checks to detection types

Added
* Initial port of image-related utility code from KWIL. This includes:
- non-maximum suppression
- `Boxes`
- `Detections`
- `Heatmap`
- `im_stack`
- `im_core`
- `im_io`
- `im_demodata`
- `im_misc`
- `util_warp`
- `im_runlen`
- `im_cv2`
- `im_alphablend`