Improvements to brace

[RubixDev]

This PR adds a new style key called outer-pointiness for the braces from the decorations library. It effectively controls the same thing as the existing pointiness but for the outer points instead. This adds the two new debug points i and j (what was i before is now k). Setting this to 0 (as is the default) provides the same behaviour as before.

I also moved documentation of the style keys from the function's doc-comment to the manual.typ file just like the other elements do it.

Screenshot of the updated example:

I am also second guessing my choice from yesterday in #227 that a pointiness of 0 is the maximum. Intuitively I would expect 1 to be the max, but then again with the angles it makes sense to have 0deg as the max 🤷. If you think we should change this I could quickly edit this PR or create another one, but that would of course immediately break backwards compatibility with v0.1.2.

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Also unrelated to the PR: I noticed the example code in the manual is justified which I think doesn't look good in code snippets. And the default font inside the example canvases is also monospace.

[RubixDev]

I also just noticed an issue with the flip toggle: because internally it just swaps the start and end positions the final move-to(end) call then actually moves to the start position, which is not what users expect. I pushed a quick fix that the move-to checks for the flip value.

[RubixDev]

I pushed a quick fix that the move-to checks for the flip value.

Actually that's still not perfect when used as part of a merge-path. I'll work on a better fix in a bit.

[RubixDev]

Actually that's still not perfect when used as part of a merge-path.

Ok that's resolved. Flipping now works by negating the amplitude and pointiness values, which doesn't have these issues.

Additionally I improved the assertion messages and added a debug-text-size style option, so this PR is now just general polishing of yesterdays work in #227.

[johannes-wolf]

LGTM.