Let Sponge::start take io-pattern as impl Into<Vec<Call>>

[moCello]

Summary

Currently the io-pattern needs to be passed to Sponge::start as a Vec<Call> but it would be much more convenient to have it take any type that is impl AsRef<[Call]>.

[moCello]

With the above Sponge would need to carry a the io-pattern as a reference to slice of Call but I would prefer to have the Sponge own the io-pattern.

Solution is to give io-pattern as impl Into<Vec<Call>> as this gives the Sponge struct ownership of the io-pattern while being as unrestrictive as possible.