Make fzf optional to avoid requiring Go

[barracuda156]

@Benexl Could we make fzf optional? Requiring it means this cannot be used on any platform where Go is broken (a lot of macOS versions, any Linux or *BSD on 32-bit powerpc, etc.).

[Benexl]

That would be very hard, how would suggest for it to be done

[barracuda156]

In a similar topic this was suggested as an alternative: https://github.com/rcmdnk/sentaku