Post-release version for the v6.1 release
add #:post condition to meta functions
add Burke as an author of Redex
meta/pkg-build: fix step order
raco pkg catalog-archive: handle interrupted update

While `catalog-archive` cannot handle arbitrary corruption of
a previous archive run, it should be able to handle a state
due to interruption or other transient errors.

Merge to v6.1.
meta/pkg-build: avoid losing docs due to transient errors

When assembling documentation, preserve any documentation previously built
for a package whose build currently fails.
Make the HTTP request method and body explicit in http-client tests
Add additional tests for HTTP PUT with request body content
Allow http-conn-send! to take a procedure as its #:data parameter
Generalized types for ((call)|(let))/[ec]c to allow n-ary continuations.
Fixed support for valuesdots with let/ec.
Moved type transformation logic out of annotate-classes back into prims.
spelling errors
fix misspelling tracker

please include on the release branch
add test case for new behavior (that I think was
legtimately a bug before the recent change
to metafunction contracts that added #:post)
fix uses of uninitilized memory

Thanks to memcheck. (I'm unable to get far with Racket and memcheck,
but I get this far.)

Merge to v6.1.
fix order of file close and kqueue de-registration

Thanks to memcheck.

Merge to v6.1.
fix protected-export checking in `dynamic-require`

The `dynamic-require` funciton was not checking correctly for
re-exported bindings.
fix guard on references to unsafe functions in bytecode

The protection against unsafe-function references was designed for
bytecode that referred to unsafe operations indirectly, and that
was broken when the compiler changed to refer to unsafe functions
directly in bytecode (to simplify JIT inlining bytecode optimization).
Actually, the relevant code (now removed) seems to be pointless,
since protected-binding checking should cover it already. Maybe
something else changed, or maybe the code was not properly checked
in the first place.

Now, `read` rejects a bytecode stream if it contains a direct
reference to an unsafe function and the code inspector is not the
original code inspector. It's still possible to synthesize bytecode
that contains an indirect reference, and then protected-binding
checking does its job.
improve the random checking for ->i so that it can exercise
simple ->i contracts

specifically, ones with no dependency. This is useful for
when there are dependent #:post conditions (which can't be
expressed with the other combinators)