SRFI docs: fix inclusion of static, standard documents
package system: change syntax of a GitHub package source to "git://..."

Besides changing the URL scheme, the tag or branch is optional and
specified as a fragment (inspired by npm). Also, any subpath is expressed
as a "path=..." query (which similarly avoids giving a different meaning
to URLs than `git' itself would). The repository name can have a ".git"
suffix.

The "github://..." format is still supported for compatibility, but
`--type github' adds "git://..." instead of "github://..." if
neither is already present (which is incompatible, since branches
and tags are handled differently for the two forms).

Closes PR 13656

(See the PR for a discussion and my rationale for this choice.)
properly guard use of andmap in redex
change the default colors a bit based on color-blindness feedback

- paren color from brown to a neon blue
- string and number constants from green to a bright purple
- lighten the comment color

the basic problem is to try to keep the red error color very distinct
from the others and try to keep the others distinct from each other
(but that's less important)
Fix contract
Sync script update re reorg
Fixing PR13973
Speed up test
Adding net/http-client and using it underneath net/url
Fix typo
Fix hash-clear doc typos
ARM JIT: fix soft-float `round'

Use our own implementation of round(), since the round()
function might be missing.
ARM JIT: avoid direct use of __aeabi_... for software fp
fix `{put,head}-[im]pure-port'

Connection wasn't converted to a port, and included a repeated
layer of chunk decoding.
adjust DrRacket to not compile files in installation's "share"

This rule supplements the old (but now less applicable) rule to
never add debugging-compiled files in the main installation's
"collects" directory.

Note that the new rule does not prevent compilation in
main-distribution packages that are linked, as in the development mode
set up by `make' in the Racet repository's top-level directory.
I think that's probably ok, since the intent of the check is mainly
just to not write to shared installation spaces, which shouldn't be
an issue for development mode.
update Guide to describe adding a collection via a package
ARM JIT: fix test for VFP

Having `__VFP_FP__` defined does not mean that VFP instructions are
available; it just means that floating-point is native-endian.

According to

 https://wiki.debian.org/ArmEabiPort

the absence of `__SOFTFP__` combined with the precense of `__VFP_FP__`
can mean VFP, though.