Sort list of items that requires to grant the Write access by their clocks

[pashoo2]

https://github.com/orbitdb/ipfs-log/blob/17cc191f0b253e881539ca1c91e59d65b89ba6e9/src/log.js#L398

E.g. i need it to compare the previous item stored in the DB with the item, that requests a write access currently. So i need the previous item in comparison by their clock time, not by items they are added.

And, maybe, even better to pass all the lists of a new and a stored items to the "canAppend" callback