Make standalone annotation use #f instead of #'#f.
Move from type-ascription-property to add-ann.
Remove check for type-ascription property.
Add #%expression around annotations.
Cleanup type-ascription.
Remove obsolete special casing for ann and inst.
Change ascription to annotate the #%expression.

Also remove the now useless type-annotation tests.
Make external check be on an #%expression.
Split out tc-expression to a separate file.
pkg/lib: add `#:catalogs` & `#:set-catalogs?` args to `pkg-catalog-update-local`

These additions allow the GUI package manager to use `pkg-catalog-upload-local`
instead of having a its own copy of the same opertation. Not surprisingly,
with two copies of the code, the `pkg/lib` copy was missing support for tags.
racket/base: add `#:for-module?` argument to `open-input-file`

Exposes a feature that is used by the default load handler to
raise `exn:fail:{syntax,filesystem}:missing-module` exceptions.
racket/gui: adapt `text-editor-load-handler` to missing-module exception

Raise `exn:fail:{filesystem,syntax}:missing-module` instead of
`exn:fail:filesystem` when a module file does not exist.
scribble/manual: clicking on a section title shows linking information

Thanks to Matthew Butterick for help and advice.
add missing @history[]
fix contract-stronger for struct/dc with #:inv clauses
distro-build: fix Windows client setup
config: add `doc-open-url` configuration

This configuration option is a better way to redirect documentation
access (at a place like NEU) than patching "search.rkt".
setup/unixstyle-install: preserve all other config entries

Preserve any configuration entry that is not explicitly set,
as opposed to keeping only entries that are known to the
script.
raco pkg config: add `doc-open-url` key
Adjust `open-input-file` type for new keyword