Transform matrix of get_image_bbox() does not always detect image mirroring

[JorjMcKie]

Please provide all mandatory information!

Describe the bug (mandatory)

The algorithm computing the image transformation matrix in page.get_image_bbox() will not always correctly reflect whether an image has been flipped (left-right or top-bottom).
This only affects the matrix returned by page.get_image_bbox(item, transform=True). The bbox itself is correct.
Also refer to discussion #1217.

To Reproduce (mandatory)

Explain the steps to reproduce the behavior, For example, include a minimal code snippet, example files, etc.

Expected behavior (optional)

Describe what you expected to happen (if not obvious).

Screenshots (optional)

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Your configuration (mandatory)

Affects all platforms.

Additional context (optional)

As an intermediate solution, page.get_image_rects(item, transform=True)[0] can be used. This should deliver the correct transformation matrix.
In the next version, this intermediate solution will replace the original.

[JorjMcKie]

new version 1.18.18 now on PyPI