meta/pkg-build: edit the "about" page
make `read-line` interruptable on a primitive port

Closes PR 14800

Merge to v6.1.1
fix a contract example in the documentation

closes PR 14798 (the previous commit, 86017992ab, that
claimed to fix this PR is unrelated; sorry for that)

Please include in 6.1.1
Update libffi to 3.1

Update libffi to 3.1 to add support for new architectures.
libffi: restore some small patches

Also, revert file-permission changes.
Add deftech for fallback/default methods in docs
Move racket-mode to the top of suggested emacs modes.
Add pointer to Sublime Text support.
fix incorrect interpretation of 'eof in new find-string implementation
racket/file: add `make-parent-directory*`

Also, clarify behavior of `make-directory*` in the case of a relative
path when the current directory does not exist.
remove internal `sorted-dirlist` function

The result of `directory-list` is now sorted by default, so the
extra function is not needed.
compiler/zo-marshal: allow extflonum literals
move find-string tests into the wxme test suite
generalize the support for mouseover tooltips so that
the computation of the string doesn't have to happen
during macro expansion, but can happen only when check syntax
is in the picture
libffi: fix problems with gcc-4.0 on 32-bit Mac OS X

Based in part on https://trac.macports.org/changeset/122079
another attempt to eliminate references to the original
installation directory from the drracket tool docs

please include in 6.1.1
Avoid requires of contracts when they're not used.

This changes when various libraries that provide contract
support to possible contracted bindings to declare when
those bindings are needed.

Probably, each static-contract combinator should manually
add to the list, instead of having one fixed static list,
but this is a start.

Saves about 10ms in startup for an empty TR module on my
laptop.

Thanks to Robby for the idea.
Add implies from typed-racket-lib to unstable-contract-lib.

Typed Racket, as of 8ea8c54eb, can add explicit require lines
to the expanded module, which can confuse the dependency
analyzer. An explicit implies declaration avoids the problem,
although I'm not sure that this is the right solution.
Send thunks to check-syntax for type tooltips

This avoids the cost of computing the printed types
to some degree. It still does have overhead (~5%) over
not computing anything related to tooltips because of
the cost of traversing the type table and computing
tooltip locations.
add the get-autowrap-bitmap-width method to text%