xilem_web: stroke-linejoin

[burrbull]

This PR adds stroke-linejoin attribute for pathes.

But it is not complete as requires kurbo::Stroke defaults to be changed to correspond to SVG defaults:

Join::Miter and Cap::Butt.

cc @Philipp-M

[Philipp-M]

Hmm interesting, I don't think it necessarily needs to be changed in kurbo (I'm not sure about the choices about the defaults, there might be a reason for Join::Round).
As this is "opinionated" around kurbo shapes I think it's fine to take whatever the defaults in kurbo are.
There's still attr to be used directly in case the "raw" svg API is preferred (or otherwise of course setting a different join in kurbo::Stroke).

[burrbull]

I'm not sure about the choices about the defaults, there might be a reason for Join::Round

Maybe.

In this case there should be another new_svg or svg_default constructor for kurbo::Stroke to prevent adding linejoin in path if it is missed.

[Philipp-M]

You might want to start a zulip thread or a PR in kurbo changing the defaults to spark a discussion why these are the defaults.

I personally don't think it's too bad to have it added by default, when using the Stroke view. It's simple to change it to the svg defaults. But having a dedicated constructor in kurbo for svg defaults is likely useful in case the defaults chosen are deliberate.