Image version 0.72.0

Changed

• Breaking: Unifies background handling under a single :background option across Image.embed/4, Image.flatten/2, Image.join/2, Image.rotate/3 and the affine family (Image.affine/3, Image.translate/4, Image.shear/4, Image.warp_perspective/4), replacing the previous :background_color and :background_transparency options. Set a transparent or semi-transparent fill by wrapping any color as {color, alpha: a}. Thanks to @hlindset for the PR.

• Breaking: An omitted or nil :background now defers to libvips' native fill everywhere (transparent for alpha images, black otherwise, paper-white in CMYK), so Image.flatten/2 with no background matches how Image.write/3 flattens. Previously Image.flatten/2 and an alpha Image.embed/4 defaulted to opaque black.

Removed

• Breaking: Removes the :black and :white extend modes from Image.embed/4 and narrows the affine-family :extend_mode to :background | :copy; combining a content extend mode with an explicit :background now errors. Use an explicit :background color in place of the removed modes. Thanks to @hlindset for the PR.

Fixed

• Fix numeric array save options (for example background: [0, 128, 0]) being silently dropped on :memory and stream writes; the filename suffix joined array values with : rather than spaces, which libvips ignores. Thanks to @hlindset for the PR.