avoid calling pkg->path from DrRacket's manager-skip-file-handler
Revert "avoid calling pkg->path from DrRacket's manager-skip-file-handler"

The reverted commit assumed that all pkgs were in either (get-pkgs-search-dirs)
or (find-user-pkgs-dir), which is a bogus assumption

This reverts commit b600dcc7bcd3783768f30aed81680a981a408d44.
Cut out class dependencies for typed/racket/base

Use (require typed/racket/class) for classes when
using #lang typed/racket/base
Fix for commit dd239f3

Forgot to commit the edits to the tests for the
reorganization in the last commit.
Remove unused require in class-prims
a start on a system to explore that classic "let polymorphism+ref cells" bug

so far, we've got the buggy let rule and polymorphism going
still need to do ref cells, tho
ffi/unsafe/com: fix VT_BOOL representation

A VT_BOOL isn't a _bool; it's a 16-bit #xFFFF or #x0000.

Closes PR 14425
add ref cells and make primitives behave polymorphically and some general cleanup
racket/gui gtk: fix -singleInstance mode and relative paths
racket/gui gtk: fix -singleInstance for paths that don't work as strings

Just in case a relative path turned into an absolute path doesn't
work as a string, add support for a bytes encoding.
fix a very very old bug in Redex uncovered by the new enumerator

The new test case in this commit shows the bad behavior;
the fix was to replace the regexp #rx".*[^0-9]([0-9]+)$"
with #rx"([0-9]+)$", ie make the regexp work properly in
the empty case (since regexps promise to find longest matches
anyway).

Also, Rackety
Add in let-poly bugs

also, misc clean ups of let-poly
adjust check function to properly deal with the store
adjust let-poly check functions so they count exns as failure,
but only for the bugs that are expected to show up that way
tweak run-muts to clarify args in help
adjust benchmark so that the 'check' functions are required to be
self-contained (and then don't call type-check anymore
from the benchmark scripts)

this fixes a problem in the let-poly models, since some
of the bugs there cause the type-checker to raise an error
add missing require
fix printout
smaller counter example for let-poly-4
fix let-poly's check function so it always terminates