fix scribble interaction error msg

fix error msg when scribble interaction #:eval
does not have sandbox-error-output set to 'string
Synch German string constants with latest.
make installer: option to set address & port where server listened

Client SSH connections now create remote port forwarding port back
to the server, so that making the server listen only on "localhost"
provides an easy improvement for security (except that remote port
forwarding seems not to work with freeSSHd on Windows).
make installer: make Windows work with bash-serving sshd

Makes a Windows build client work with Cygwin's opensshd.
make installers: make the server listen only to "localhost" by default

This makes the build more secure, but it's a backward-incompatible change.
To adapt old site-configuration scripts, the simplest option is to set
`#:server' to "localhost" everywhere and rely on SSH tunneling to let
a client reach a server (though, unfortunately, that option doesn't
seem to work if a Windows machine uses freeSSHd). Another possibility
is to se `#:server-hosts' to the empty list.
Mac OS X: make updated frameowrk paths a multiple of 8

Needed for code-signing (on 64-bit builds, at least)
make installer: add Mac OS X code-signing support
make snapshot-site: add "current" links for installers
Fix Reference contract typos
Split out `redex-gui-lib` and `redex-pict-lib` packages.
Move distributed places tests to their own package.
Edit `racket-test` requires.
Move timing test for typed futures to benchmark collection.
`racket-test` needs `pconvert-lib`.
Remove now-redundant prop.
Fix pkg infor for `distributed-places-test`.
Check that all in-repository packages have description and authors.
actually fix PR 14102

This commit definitely takes the position that
"beautiful" code is less important than reasonable
error messages; better if the code were refactored
so the names flow through it more gracefully
Add access to the failure continuation in `match`.
fix bug in 82bb5ba4c8; also add test case