Skill tree additions and restructurings

[oli-obk]

No description provided.

[RalfJung]

Other things:

• the "mutable ref in final value" node needs renaming; the feature we want is "mutable ref in const items".
• <int>::from_str as a specific subitem of FromStr seems rather arbitrary? I'd probably remove it, that seems less confusing.
• would it make sense to give the feature name everywhere? That makes it easier to match things up. (I have been adding the feature name to issue titles wherever I noticed they are missing, which makes the tracing issues much easier to find in my browser history.)

[oli-obk]

* `<int>::from_str` as a specific subitem of `FromStr` seems rather arbitrary? I'd probably remove it, that seems less confusing.

that has its own issue, thus I added it at all.

* would it make sense to give the feature name everywhere?

yes, but that makes everything more verbose. I've been trimming down the graph where I can

[RalfJung]

that has its own issue, thus I added it at all.

FromStr has a tracking issue. But I was talking about the <int>::from_str.

yes, but that makes everything more verbose. I've been trimming down the graph where I can

I mean it makes it more informative, I wouldn't call that "verbose".^^ When reading a tracking issue, right now it's non-trivial to figure out where in this tree that issue is located.

[oli-obk]

I added all the feature gate names where on existed

[RalfJung]

Awesome!

What does fg: mean? Oh, "feature gate" I guess... isn't it usually called a "feature flag"?
Is just using feature: too long?

[oli-obk]

I moved to feature and did some smaller textual changes that shrink the tree's width again

[RalfJung]

Thanks a lot! Let's merge this so we can see how it looks rendered.