Support for fish

[tbodt]

Fish's history includes a little more information than just the command that was executed. ~/.local/share/fish/fish_history is a yaml file, here's a sample:

- cmd: v /usr/local/etc/rethinkdb.conf 
  when: 1492027898
  paths:
    - /usr/local/etc/rethinkdb.conf

As you can see it includes the command, a timestamp, and the filepaths references by the command.

[jcsalterego]

Whew! Unfortunately since historian is purely bash right now, we'd need some sort of... bash yaml parser (cc @mando).

This might be out of historian's depth :\

[mando]

I KNEW THIS DAY WOULD COME!

[jcsalterego]

@tbodt After some further consideration, I think proper YAML parsing won't be possible until historian is rewritten in something other than bash. I'm gonna go ahead and close the issue but I'll keep it in mind if I ever do a rewrite. Thanks!