Xmldiff

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- Used geometric mean for the node_ratio, for better handling of simple nodes.

- Added an experimental --best-match method that is slower, but generate
smaller diffs when you have many nodes that are similar.

- The -F argument now also affects the --fast-match stage.

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- Make it possible to adjust the attributes considered when comparing nodes.

- Python versions 3.7 to 3.11 are now supported.

- Improved node matching method, that puts more emphasis similarities than
differences when weighing attributes vs children.

- Added a parameter to return error code 1 when there are differences between the files

- Added a parameter for ignoring attributes in comparison.

- Solved a bug in xmlpatch in certain namespace situations.

- Added a --diff-encoding parameter to xmlpatch, to support diff-files that are
not in your system default encoding.

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- Added an option to pass pairs of (element, attr) as unique
attributes for tree matching. Exposed this option on the command
line, too.

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- Added a simple ``xmlpatch`` command and API.

- Multiple updates to documentation and code style

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- A workaround for dealing with top level comments and the xml formatter

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- Changed the substitution unicode character area to use the Private Use Area
in BMP(0), to support narrow Python builds

- Added --unique-attributes argument.