We keep __fish_is_nth_token for compatibility and edit the
implementations of __fish_is_nth_token, __fish_is_first_token and
__fish_is_token_n to use fish_is_nth_token
Apparently that's actually faster than jq, and it's more likely to be
installed.
Also it should convince the arch packager to remove the jq dependency.
The indentation is weird, though.
[ci skip]
bower was calling `__fish_should_complete_args`, the old name for
`__fish_should_complete_switches.`
yarn was parsing bower.json instead of package.json.
