Might as well annotate methods which can't take nil
Exception handler to try and track down assertion failures
Exit processing loop in the even of a cancellation
Clear out multi handle as part of dealloc cleanup
Clean up queue during dealloc too
Nothing for shutdown to do when not use multi-socket backend
Ignore multiple cleanups
Serialise access to multi during cleanup too
Run cancellation test like any other

CURLTransfer notifies its delegate when cancelled, much like
NSURLSessionTask
Disable FTP multi tests

It seems cleanup of the multi tries to do something with its open FTP
sockets, which hangs indefinitely. I believe that’s because the mock
server has gone away
Order tests by our preferred backend
Don't test own multi

Tends to hang cleaning up after FTP mock server connections
Merge branch 'v4.x-beta' into darwinssl-get-trust

Conflicts:
	CURLHandleSource/CURLMultiHandle.m