It may not be perfect and taste is debatable, but surrendering the
formatting to a tool improves uniformity and liberates us from
having to care about it ourselves. Small excpetions being the
formatting of comments and the introduction of comment lines as an
aid for humans to quickly distinguish modules from each other (tidy
cannot work with empty lines for that), those remain manual tasks.

Reformat comments to a uniform block style.

Add small empty comment lines to visually separate modules from each
other in cases where there is no existing comment to fulfil that
purpose.

Fix some minor XML errors like duplicate closing tags.

Use empty elements where appropriate, i.e. mostly turning
"<branch foo=bar></branch>" into "<branch foo=bar />".

Accept some "formatting weirdness" where tidy introduces empty lines
(sometimes with, sometimes without whitespace characters) for reasons
unknown. It happens depending on length of line, so it is
deterministic.