Autocomplete should work with a single letter when unique

[derekargueta]

In the example below, I have the public directory, the only directory that starts with a p. But when I try cd p + tab, it doesn't autocomplete. It works if I add a u, but since it's the only item starting with a p the autocomplete should work anyways.

[zackargyle]

Good catch! So it actually is working "correctly", but the current autocomplete implementation was always including commands as well. Since there is was multiple suggestions ['pwd','public'] it was not suggesting one. Made a PR to fix the autocomplete to only include commands if we are autocompleting a single token.
#8