Revised installer tests.

* The first change is probably due to a difference in my $LANG, so it
  might be better to set it to a known value for testing.

* The second change in an explanation about a corner case in the
  installer that would be nice to fix, if it's still done in a similar
  way.
Synch German string constants with latest.
Remove install-pkg-inferred-as duplicate
raco pkg {install,remove}: promotion from & demotion to auto-installed

When you `raco pkg install' a package that is already present as
an auto-installed package, the installation is promoted to
an explicitly installed package.

When you `raco pkg remove --demote' a package, then it is changed
from an explicitly installed package to an auto-installed package.
Combine `--demote' with `--auto' to remove a package only
if there are no dependencies, leaving it auto-installed otherwise.

The defaults (promote in the case of `install', not demote in the case
of `remove') are different because it seems more likely that you
really mean to remove a package when using `pkg remove', while it
seems likely that you just want to start using a package that happened
to be auto-installed already for `pkg install'.

Also, make the package scope inferred for `raco pkg' commands
that take a list of package names, and fix up lock handling and
error reporting.
scribble: fix list splicing for sections
overhaul documentation for the package manager
add missing lock acquire
fix exprs field for raise-syntax-error*
added nearest below & above to find-seconds error message

Closes PR 13945
remove prohibition on `handle-evt?' arguments to `wrap-evt', etc.

The intent of disallowing `handle-evt?' arguments to `wrap-evt',
`handle-evt', and `chaperone-evt' was that those extra wrappers
break the tail-handling behavior that is almost certainly intended
when `handle-evt' is used. The extra checking was not obviously
worthwhile (we don't have any checked "this procedure should be called
in tail position" annotations, after all), and pushing the distinction
through Typed Racket looked particularly inconvenient.

Dropping the constraint is trivial if we say that wrapping a
`handle-evt' result disables the tail invocation of the handler
procedure.
Revert "make user PLaneT install path use installation name instead of version"

This reverts commit ac20e7fc0d0e60874cc0b47e5d15727e412f5500.

Using the installation name name seems right, but it creates sandbox
trouble, since finding the instalation name requires several
path-chasing steps. I think the sandbox problem shoudl be fixed,
somehow, but since I don't have a good idea right now, I'm reverting
the PLaneT change.
set the background and the foreground color (not just the foreground)
when switching to white-on-black mode (or back).

this causes the cursor in embedded editors to pick up the right colors
(since it is selected by the inverse of the background color of the style
of the enclosing editor snip)

closes PR 13943
fix exit:exit docs

closes PR 13944
Update documentation source location link
fix typos in macro guide
Increase DrDr benchmark timeout
Fix mrlib doc typo
Fix guide typo.

Closes PR13955.
fix bytecode-format bug

The range of values used to represent "improper lists"
of length 36 to 65 overlapped with the range of values
used to represent other things.

This bug is the new chapion of the "how did we not hit that
earlier?" category. The bug was introduced around v300, at
the latest.
adjust `compiler/zo-marshal' for bytecode-file change

Forgot to fix as part of b8db5aacb3.