Although it should never happen that a file descriptor is suddenly
closed, it appeared that this happens on linux 64bit when using
FMODex... Not really sure how useful this is, but at least now the
viewer just continues to work, as if -say- the socket was closed
remotely. Before the curl thread would go into a tight loop that it
wouldn't recover from until the watchdog thread terminated the viewer.
Moved AICurlPrivate::Stats to AICurlInterface::Stats and added several
counters to keep track of the number of existing instances of
respectively AICurlEasyRequest, AICurlEasyRequestStateMachine,
BufferedCurlEasyRequest, ResponderBase and
ThreadSafeBufferedCurlEasyRequest.
Every curl transaction is a AICurlEasyRequestStateMachine which has a
AICurlEasyRequest as member, which is a reference counting pointer to
a ThreadSafeBufferedCurlEasyRequest. And now BufferedCurlEasyRequest is
derived from CurlEasyRequest which is derived from CurlEasyHandle, but
neither are used separatedly.