Option for custom sort in autocomplete

[ChildishGiant]

Currently you can specify a custom "sortFunction" but this only controls which element wins in a 1v1 matchup, not how the matchups are made (Currently just uses array.sort). Adding this would allow end users to use libraries such as fuse.js to do more complex sorting and make results more accurate.

[ChildishGiant]

I have a functioning PR, just working on docs for it. This'd be a 2.0.0 feature as sortFunction has been renamed to compareFunction to avoid confusion and that would be a breaking change. I could always just keep it as sortFunction but having a sortFunction and customSort that do different things is rather confusing.

[wuda-io]

Can be done now with the new onSearch Function. #261