meta/pkg-build: conflict checking needs all packages
meta/pkg-build: support parallel builds

Support multiple VMs to run package builds parallel.
main doc page: use `margin-note` instead of `margin-note*`

The rendered form of `margin-note` does the right thing with a narrow
view, unlike the new rendering of `margin-note*`.

Also, wrap `not-on-the-web` only around the part that claims
an installation-specific listing, and add `not-on-the-web` to
"doc-site.css" for "docs.racket-lang.org". I think it's good
for :docs.racket-lang.org" to explain how to open documentation
locally, which is why I didn't make `not-on-the-web` work
as a block wrapper.
Improve triggering for generalizing lists.
Cleanup type-env-structs.

Removes all unused functions and cleans up the remaining ones to have
more consistent and simpler APIs.
Fix docs for `takef`

Closes PR 14619
Make tc/funapp follow contract in error case.

Closes PR 14615.
Fix typechecking of list* with no args.
Make with-type disarm/arm the body expressions.

Closes PR 14587.
bump version number for change mentioned in commit 83e8cfbafebd47406fc518d007de1eade0757140
bump version number for abbreviate-given-names addition

(from commit 74831b41cc2589af94a4e7cc6ffefa1d8809226c)
bump version number for change mentioned in 145644ace4187c9c9376e00f2d271aaf23a61d4c
add @history[] note for change in 0a0c62a1e606e9e668cfe9bb20dfa628e6657d7c
add @history[] note for change in ddb74774941a3c3fcc1c4162b8fde3168435a302
make double-clicking in the list box for the "Open Collection Path..."
menu item work
spell check
add --letterbox to control the color of the letterbox
fix metafunction rewriting

in the case that the bad use of the metafunction appears as the first
thing in a good metafunction application

closes PR 14618
propagate some source locations for better error reporting

related to PR 14595
Fix array tests after TR change