This augments the previous change for issue #3346 by adding an error
message when an invalid integer is seen. This change is likely to be
controversial so I'm not going to squash it into the previous change.
It seems that `ul` can't handle the escape sequences for bold text that `nroff` generates on my system. Fixed by either removing `| ul`, or adding `-c` to the `nroff` command.
Needs testing for old (OSX?) versions of nroff.
The terminal width magic that __fish_print_help learned doesn't help
when builtin_print_help runs it in a subshell. Instead, add an
undocumented --tty-width flag to __fish_print_help that's used to pass
the terminal width.
As a result of this rewrite, the output now:
* Expands to fit the terminal width, like `man` does
* Preprocesses the manpage with `tbl` just in case, since `man` does
this, even though I doubt any fish manpages use `tbl` formatting.
* Handle bold/underline with the `ul` command as it was designed for
instead of trying to fake it with `sed`.
* Compresses blank lines as `man` does with the default `less -is`
pager.
