Kwimage

Changed

* `kwimage.structs.*.warp` can now accept a `kwimage.Affine` object.

Added

* `Boxes.to_slices`
* `Affine.concise`


Fixed

* counterclockwise polygon check


Changed

* improvements to `kwimage.Affine`.

Fixed

* Fixed failure in Affine.coerce
* Fixed random test failure in Boxes

Added

* New CI for building wheels with cibuildwheel
* Checkerboard demo image
* `warp_affine` with optional antialiasing for downsample operations.
* `imresize` now has optional antialiasing.
* `Affine.decompose` which extracts the scale, translation, rotation, and shear
from an affine matrix.


Changed
* `imscale` is deprecated and now results in an error
* `warp_image`, which did not do what you think it does, is deprecated and now results in an error

Added
* New `transform.py` module

Fixed
* Fixed numpy warning by using `float` instead of `np.float`.

Changed
* Errors instead of warns for opencv import issues
* Warp methods now treat None as the identity transform.
* `kwimage.num_channels` no longer errors when the number of channels is not 1, 3, or 4.