- Set their view boxes to the original height and width, so they are
  guaranteed to present correctly.
- For Figure 17-02, use the trick of adding a hidden node and hidden
  arrow to it in “Task 2” to align the two boxes.

- Create a section (which will be deleted or at least reintegrated once
  all is said and done) to hold content pulled out of other sections for
  the sake of clearer flow and understanding.
- Pull “advanced” material from 17.00, 17.01, and 17.02 into the holding
  section and start reorganizing their content to account for shifting
  around materials.

In addition to the baseline changes, skip over non-directory code where
directories are needed to deal with things like `.DS_Store` files. Also
add a bunch of context on error causes from `std::io::Error` because it
was *impossible* to figure out exactly what the source of those were.

Upgrade to Rust 1.81

Use immutable borrow of `TcpStream` when creating `BufReader`

Add `cargo init` usage suggestion to 1.3

Fixes #4018

Update build instructions: include mdbook plugins

The `block_on` name is what both Tokio and smol use, but it is a bit
obscure from the point of view of introducing this material. `run` says
much more clearly what it does *for the level we care about here*, I
think.

These make up *most* of the rest of the edits I caught while rereading
which are not *major structural revisions*, along with some of the bits
required for those major structural revisions.

This does *not* yet incorporate any of the relevant feedback from Carol
on this, so a couple spots are still pretty messy.

Along with the wording and phrasing-level edits, pull out a fair bit of
material for the “advanced” section at the end, specifically the details
of what `Stream` and `StreamExt` actually do.

Bonus: fix some style guide issues, too!

Co-authored-by: Carol (Nichols || Goulding) <carol.nichols@gmail.com>
Co-authored-by: James Munns <james@onevariable.com>
Co-authored-by: Tim McNamara <paperless@timmcnamara.co.nz>

Co-authored-by: James Munns <james@onevariable.com>

Co-authored-by: Tim McNamara <paperless@timmcnamara.co.nz>
Co-authored-by: Carol (Nichols || Goulding) <carol.nichols@gmail.com>

I accidentally copied these in when pulling in the `trpl-note` mdbook
preprocessor many months ago, and we did not notice amidst the many
other changes in that PR!

Add `reqwest` and `scraper` dependencies to the `trpl` crate. Wrap them
in `trpl` re-exports which keep the API surface low.

Rewrite the whole first section to use `race` along with those `trpl`
re-exports to show a more “real” example of async code right form the
start, including actual concurrency, unlike the previous introduction.

Update 17.03 to account for having introduced `race` already, and update
listing numbers for rewritten 17.01.