Enhanace generator instances to whitelist creation instance

[lllwvlvwlll]

Currently, generator instances only support automatic whitelisting of a the creator's address. This enhancement will expose a generator instance creation path which automatically whitelists the scriptHash of the creating contract as well as a code (when an instance is created in-contract). This will enable generator instances to be instantiated and immediately used within contracts.

A good example usecase for this routine is the random occurrence of some object which needs to be procedurally generated at the time of occurrence. By calling a create generator instance method, the user receives the instance ID and can immediately use the instance which the need for a second contract call to whitelist the calling instance.

[roschler]

@lllwvlvwlll "which the need for a second contract call to whitelist the calling instance."

without the need for a second contract call to whitelist the calling instance ?