adjust contract-out.rkt to work when it is compiled
adjust framework tests to properly find the racket executable
racket/gui: fix `get-key-release-code' result for a key-press event

Return 'press (matching docs and pre-v5.1) insteda of 'down.
Add ".desktop" file support

A launcher can have a ".desktop" file (found like other files: as the
same name as the main launcher file, but with a ".desktop" suffix),
where the "Exec" and "Icon" fields are added automatically. A ".png"
or ".ico" file can be supplied for the icon (where the ".ico" file
is already used for Windows launchers).

Closes PR 13953

Fix various problems with Unix-style install from an installer.

Also, add an ugly icon for the Racket Package Manager, with the hope
that it will provoke someone to create a nicer one.
try to be more accomodating to low-permission contexts
when reading the development links file
Added get-path-bounding-box.
Added get-path-bounding-box take 2
with-color and with-thickness now preserve pen cap and join
make a drracket-plugin-lib pkg for other pkgs that provide plugins
to depend on (so they don't have to depend on all of drracket)
move slideshow plugin to its own pkg
move rackunit's drracket plugin into its own pkg,
that you can now get via the (new) 'rackunit' pkg
adjust dependencies to depend only on drracket-plugin-lib
where it seems reasonable to do so
tests for Xexpr readers
batch io revised with X-expression reader, plus tests
bug fix in test
documentation for Xexpr readers and auxiliaries
directory-list: always sort results

Consistently sorting shouldn't cost much relative to the
cost of `directory-list' (except for the path->bytes conversion?),
and it makes directory traversals (including archive packaging)
more deterministic across runs and platforms.

(Eli suggested this a long time ago.)
add `path<?' and `symbol<?'

These comparisons are useful for sorting while avoiding the overhead
of conversions to bytes or strings.

Having `path<' reduces the cost of sorting in `directory-list'.
GUI package manager: catch and report errors
official catalog server: allow package addition via update API