Improve type of make-immutable-hash.

Closes PR13297.
Fixes *-filter types and filter of zero?.

Closes PR13275.
configure: add more guidance/reporting on non-recommended options
ffi/unsafe: fix a bug in conversion to UTF-16

Characters outside of the BMP were translated incorrectly.
JIT: fix bug in checking certain values before unboxing

The check was incomplete in the case that both arguments to a binary
[ext]flonum function need to be checked and the second one was not an
[ext]flonum and also not a fixnum.
scribble: preserve order of ".js", ".css", and ".tex" additions
add parameterize* to tabing and smart opening square bracket pref defaults
interactivity fix for online check syntax

commit e503850f21aab20234f580c9e14c7e3764383e80 broke drracket's
interactivity (for some files it could take 2 seconds to do
that one line)

This changes the bindings-table so that it maps to sets instead of
lists. Now, instead of mutating all entries in the table right after
collecting everything, just leave them as sets until we need the info
and just sort a single entry, when it is needed
ffi/unsafe: add `_size', `_ssize', `_ptrdiff', `_intmax', `_uintmax'

These additions could create backward-compatibility problems, but our
searches suggest that problems will be rare; it's more common for
`_size_t' to be incorrectly aliased to `_int', so having definitions
for these standard types is likely to avoid future problems.
racket/base: add `impersonator-ephemeron'
racket/snip: fix `style-list%' `notify-on-change' and contracts

The method uses the new `impersonator-ephemeron' function to
retain a callback as long any value that it impersonates
is reachable.
Revert "avoid a wrapper on callbacks that get stored in a weak table"

This reverts commit d1357f229430f6288d037791782b00b441cad4cb.

Commit 38d6afe07c fixes the problem more generally.
fix cross-reference
Revert most of the change to word break, but introduce a nbsp for browser metrics.

Related to PR 13305: I tried to use zero-width-space to force appropriate
line breaks, but unfortunately under Opera on Linux, this shows as
unsupported character glyphs.

Since I can't reliably use zero-width-space, I'm backtracking to the
prior solution on introducing spans with the mywbr class.  However,
I've added in a &nbsp element to the content of the span, as suggested
elsewhere on the web.  This appears to fix the _gcpointer issue that
Eric sees.
fix `plt-games' launcher
scribble: fix "on this page" rendering

A recent change improved "on this page" handling and also
fixed a short-circuit test to almost certainly do what
was originally intended, but the test was wrong, so just
get rid of it.
Improve comment.
New Racket version 5.3.3.4.
JIT: inline `char->integer' and `integer->char'
racket/draw win32: work around a Pango bug

Pango crashes (with an assertion failure) on characters U+1D173
through U+1D17A. Trying to fix (or even just compile) Pango for
Windows is hard, so skip the characters at the `draw-text' and
`text-extent' level.

The bug is unlikely to be specific to just those characters in the
long run, but only those characters appear to be problematic on my
Windows 7 installation. So, the workaround may be enough for many
installations, and hopefully the Pango bug wil be fixed one day.

Relevant to PR 13513