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Normally you can gracefull clean up in iTasks by hooking into the
onDisconnect handler, however, if the IOtask is destroyed by for example
a step, it was impossible to gracefully close the connection.

To fix this, this commit:

- Patches the tcp connections used internally (async, {web,sds}service, tonic)
- Adapts the wrapping tasks from Internal.Task
- Adapts processIOTask to get an onDestroy handler
- When an IOTask is destroyed, read the task state once more, call the
  onDestroy handler and possibly write some data once more. This can be
  used to gracefully close any connections to services that cannot
  reasonably detect broken TCP connections