Fixed several ConnOpener problems

Fixed several ConnOpener problems

... by relying on AsyncJob protections and comm_close(), while maintaining a
tighter grip on various I/O and sleep states.

Problems addressed:

* Connection descriptor was not closed when attempting to reconnect after
  failures. We now properly close on failures, sleep with descriptor closed,
  and then reopen.

* Timeout handler was not cleaned up properly in some cases, causing memory
  leaks (for the handler Pointer) and possibly timeouts that were fired (for
  then-active handler) after the connection was passed to the initiator.

* Comm close handler was not cleaned up properly.

* statCounter.syscalls.sock.closes counter was not updated on FD closure.

* Waiting pending accepts were not kicked on FD closure.

* Connection timeout was enforced for each connection attempt instead of
  applying to all attempts taken together.

and possibly other problems. The full extent of all side-effects of mishandled
race conditions and state conflicts is probably unknown.