ReadOnly: Add functions to register CALLs to a context used to handle deferal of...

ReadOnly: Add functions to register CALLs to a context used to handle deferal of processing of CALL commands.
Once the contexts are freed, the deferred calls are re-issued to the input packet processing functions again.
This is needed when/if a CALL can not currently be processed by the main engine due to the record being locked down for revoking of all delegations.

The data is passed through several layers of callbacks, and finally a timed event callback to ensure that the processing of the packet will be restarted again at the topmost eventloop, avoinding event loop nesting.