closes#82
Also added a `HISTFILE` so it always reads the correct file that the
shell is pointing to
Is there a `HISTFILE`? If so, use it
If it's Zsh: Is there a `ZDOTDIR`? Use `ZDOTDIR/.zsh_history`
If it's Fish: Is there an `XDG_DATA_HOME`? Use
`XDG_DATA_HOME/fish/fish_history`
If none of them are present, revert to the default `$HOME/...`