cares_wrap: remove superfluous 'this' keyword
cluster: fix premature 'disconnect' event

Don't emit the 'disconnect' event until all workers have gone away.
Before this commit, the event was emitted when all open handles were
closed, which usually - but not always - amounts to the same thing.

Fixes #6346.
util: format as Error if instanceof Error
crypto: add SPKAC support

Implements new class 'Certificate' within crypto object for working
with SPKAC's (signed public key & challenge) natively.
doc: crypto: document SPKAC additions

Document the SPKAC functionality that was added in commit 7f66e44.
Revert "crypto: add SPKAC support"

This reverts commit 7f66e44dc1e90e7abda2a9ed02d7e8163e1f6358.
Revert "doc: crypto: document SPKAC additions"

This reverts commit aa94450b31a28d6251df3b88fdd652ddd1e67a69.
crypto: add SPKAC support

Implements new class 'Certificate' within crypto object for working
with SPKAC's (signed public key & challenge) natively.
doc: crypto: document SPKAC additions

Document the SPKAC functionality that was added in commit 7bf46ba.
http_parser: expose pause/resume method for parser
http: provide backpressure for pipeline flood

If a client sends a lot more pipelined requests than we can handle, then
we need to provide backpressure so that the client knows to back off.
Do this by pausing both the stream and the parser itself when the
responses are not being read by the downstream client.

Fix GH-6214