fix bug in ->i
fix a test for `raco exe`

The test failed for certain installation configurations due to a
problem with the test.
raco exe: document command-line flags
sync: accept 0 arguments

As suggested by Jonathan Schuster.

Note that the `choice-evt` constructor already accepted 0 arguments.
racket/draw: fix `get-argb-pixels` for unscaled and just-alpha

Closes PR 14653

Merge to v6.1
racket/draw: fix problems with `set-argb-pixels` on scaled, no-alpha bitmaps

Also, fix the docs to clarify that `just-alpha?` as #t means a no-op for
a target bitmap that has an alpha channel.
web pages: add "recent" links at download-racket-lang.org

These links reflect soft links that are in place at
"mirror.racket-lang.org", but they're needed as links/rewrite on the
main site for some purposes, such as references from the tech-report
pages.
web pages: use UTC for computing month names

Otherwise, generated web pages can differ depending on which timezone
is used to render them.
web pages: fix platform sorting on download pages

Fix use of wrong array element during sort, where using the wrong element
caused "Windows source" to be sorted before "Windows (x86, 32-bit)".
(The wrong-element bug was introduced with changed to support the button
that downloads directly from the default mirror.)

Closes PR 14655 and PR 14656
quasisyntax: fix reporting for misused `unsyntax[-splicing]`

Closes PR 14652
meta/pkg-build/thread: fix test

Add synchronization so that the enumerated interleavings cover
all of the ones that should be possible.

Using `(sync (system-idle-evt))` as a barrier works as long as
the implementation of the library being tested doesn't itself
use `(sync (system-idle-evt))`. That seems like a safe-enough
assumption for a test.
Fix `compiled-bitmap` and `compiled-bitmap-list` on 2x bitmaps, lossy compression

This fixes the docs for `compiled-bitmap-list`. Icons in DrRacket were immune,
because they're stored in modules as PNG bytes.

Please merge to v6.1
starting off on summary integration
Adding legacy/core decision in gl-config/canvas
Move `margin-note*` in math docs to work around issue with Firefox

Please merge to v6.1
Racket-y, 102
Rackety, deleted some unnecessary comments
documented addition of check-random; please include in 6.1
raco decompile: show `provide`s
fix submodule export of enclosing module's binding

When `x` and `x`-with-a-mark are both defined, then the order of
definitions affected the binding that `(provide x)` would export
in a submodule that uses `#f` as its language. The problem was
in the implementation of the implicit `require`, which needs to
look up a variable's symbolic name in two different environments
to set up the right mapping.