Make configure install the docs in the standard place.

Closes #315 (on github)
New Racket version 5.3.4.3.
GC tweaks

In a minor collection, old-generation pages can be ignored for
the fixup pass. Also, the "moved" bit implies the "marked" bit.

Also, move the mark bits to low and the hash bits to high,
which leads to slightly better generated code for the GC.
fix the name of `environment-variables-ref'

Also, fix use of unsetenv() to work with platforms where it returns
void.
code tweaks
Fixing PR13683
Adding link
Changing default max-waiting to 511 re Apache
Adding max-waiting to serve/servlet, re dyoo
Normalize max-waiting contracts
pkg docs: add a tag for the "how to develop" section

Merge to v5.3.4
move `handin-client' and `handin-server' to `handin' package
raco setup: remove any extra documentation dirs in installation

After uninstalling a package in installation scope, its documentation
should be removed. A new `raco setup' step takes care of that.

Merge to v5.3.4
raco pkg: fix `raco setup' sensitivity to package scope

Merge to v5.3.4
dist-spec fix for `raco setup' extra file
ffi/unsafe: fix doc typo

From Tobias

Closes PR 13684

Merge to v5.3.4
Add Burke to redex responsibility

(and remove Casey)
equality for `define-cstruct'-generated wrappers

Closes PR 13650

Merge to v5.3.4
add Burke to acks

please merge to release branch
fix listof error reporting

closes PR 13685

please merge to the release branch