Allow sorting tabs by last access time.

[evrenesat]

Thanks for the tabby, it's very useful and works nicely. I have feature suggestion.

Sorting tabs in a way that the ones I've opened most recently would show up at the top of the list. Frequently I switch between same 4-5 tabs out of 50 open tabs. A feature like that would let us skip searching for most recent tabs and also help to remember what to search for if we are looking for a tab that is at the tenth place (so writing part of its name is faster than hitting down arrow ten times)