ensure that \kern inside an SVG only affects the following content

[xworld21]

When \kern happens inside an SVG group, the current code shifts the entire group, which goes wrong as soon as \kern appears after the content (hence HACK HACK HACK in the comments, I guess). I changed it so that it creates an extra <svg:g> around the previous content and translates it the opposite way before applying the new transform.

In practice, this fixes the horizontal alignment of arrow labels in xymatrix, because they use \kern before and after the label: we go from

to

Vertical alignment is obviously off; it becomes pretty good with #2488, but still visibly wrong due to unrelated depth shenanigans.

[dginev]

Workflow question: Do you have a branch with all/most of your tikz-related PRs merged? I am curious to test them in tandem. Such a branch will inevitably be a diverged one from master (as we'd like to reintegrate PR-by-PR), but could make other upgrades easier to test while the process of merging converges...

[xworld21]

Do you have a branch with all/most of your tikz-related PRs merged?

No, they are essentially orthogonal to each other, but I might as well make one for testing purposes. Even if the merged branch diverges from the smaller PRs, it should still be a close approximation. I just need a moment to rebase...