When an array is scheduled, it is providing args.

This supports various of the async nqp:: ops that pass information to
a scheduler in this way.
Rename timer cancellation handle class.
Expose underlying scheduler queue.

For the sake of things that want to use it as a target for any
asynchronous operations.
Very first pass at signal handlers.

Probably some we could support are missing (though it's an LHF for
somebody to add those), and the API is certainly up for discussion.
But now there is, at least, a way. Closing the tap doesn't in any
way remove the handler yet; that'll come later once the more general
cancellation mechanism arrives.
Tweak thread starting in queue accessor.

Create up towards the limit, rather than assuming one is enough, as
that may lead to deadlocks.
Add basic async client socket support.

Only works on MoarVM so far, missing reading bytes and robustness and
various other bits, but enough for writing a simple async HTTP client.
Provide async server sockets on MoarVM.
First pass at IO::Notification.

Provides OS-backed notification of file changes. It's a fairly raw
stream; more sophisticated things based on it can likely evolve in
module space for the time being.
Add a basic cancellation object.
Return Cancellation for time-based scheduled work.
Merge branch 'async' into nom
Bump NQP_REVISION for async improvements.
Include Cancellation.pm in JVM setting build.