Pre-Release Checklist for v6.4, second call

[Ryan Culpepper]

Checklist items for the v6.4 release
(using the v6.3.90.900 release candidate build)

Search for your name on the checklist page to find relevant items, reply
when you finish an item (please indicate which item/s is/are done). Also,
if you have any commits that should have been picked, make sure that the
changes are in.

The checklist page is at:
https://github.com/racket/racket/wiki/Release-Checklist-6.4

NOTE: You can either either edit the checklist page yourself to check
off items or reply to me and I'll check them off for you.

Important: new builds are created without announcement, usually whenever
I pick a few commits. If you need to commit changes, please make sure
you tell me to pick it into the release branch.

--> Release candidates are at
--> http://pre-release.racket-lang.org

Please use these installers (or source bundles) -- don't test from
your own git clone (don't test the `master' branch by mistake!). To
get the tests, you can do this:

cd ...racket-root...
./bin/raco pkg install -i main-distribution-test