Key delegated to block computing
The idea of the delegated key is to be able to delegate the computation of blocks to a subkey, in order to put the main keychain in safety.
This subkey has the ability to revoke the associated member account.
The member may at any time declare a new delegated Key that cancels and replaces the previous delegated Key.
To avoid spam it will be necessary to add a parameter preventing to declare a new delegated key before