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
"function --argument" is not a thing, it's "--argument-names". This only
accidentally works because our getopt is awful and allows abbreviated
long options.
Similarly, one argparse test used "--d" instead of "-d" or "--def".
I hate doing this but I am tired of touching a fish script as part of
some change and having `make style` radically change it. Which makes
editing fish scripts more painful than it needs to be. It is time to do
a wholesale reformatting of these scripts to conform to the documented
style as implemented by the `fish_indent` program.
