- Use `string collect` instead of cat to get the contents of
$FZF_DEFAULT_OPTS_FILE. Also, check if the file is readable first.
- Use `string split` instead of cut to set $FISH_MAJOR, $FISH_MINOR.
- Use `string replace` instead of perl to strip leading tabs.
- Enable using unescaped quotes for exact-match, exact-boundary-match.
- Enable suffix-exact-match.
- Enable inverse-exact-match, inverse-prefix/suffix-exact-match.
- Allow searching for double quotes and backslashes.
- Combine multiple consecutive slashes into one.
- Workaround for test command bug, allowing $dir or $commandline be a
single `!`.