fmt's -s, -t, -c options didn't work properly for long lines.

fmt's -s, -t, -c options didn't work properly for long lines.
Since get_line may end up calling put_paragraph (for long lines),
be sure to set global, `other_indent', before it is used there.

(set_other_indent): New function, factored out of...
(get_paragraph): ... here.  Call it.
(get_line): Call set_other_indent before calling flush_paragraph,
which calls fmt_paragraph, which in turn calls put_paragraph,
which uses other_indent.