Use stty when available to set tty width for tests

[dobbymoodge]

Checks for stty in path and uses it, if available, to set terminal
width (stty columns 149). This guarantees that the desired terminal
width is used for tests when the value comes from ioctl, since that
has priority over the COLUMNS env var.

This addresses an issue where tests for the output of templates that
use the termWidth template function would fail when run in certain
environments - in my case, bash running in rxvt-unicode-256color
in Fedora 30 - when the terminal width doesn't match 149 like the
test expects.

[coryb]

This will change my tty params even after the tests exit. I think we need to preserve/restore the original value to make this sane. Something like:

if command -v stty 1>/dev/null 2>/dev/null
then
    cur=$(stty size  | cut -d " " -f 2)
    stty columns 149
    restoreCols() {
        stty columns $cur
    }
    trap restoreCols INT TERM EXIT
fi

[dobbymoodge]

That makes sense, though I can't shake the feeling that there's a "right" way to set up a fake TTY for tests like this. I'll do some research when I get a minute tomorrow.

[dobbymoodge]

although it looks like #302 obviates the need for this PR; I'll double-check tomorrow and close if so.