format_stat: Manuscript-friendly number formatting
Description
Formats a numeric result (e.g., p-value) as a manuscript-friendly string in which values below a minimum cutoff (e.g., 10^-5) are
reported for example as "< 10^-5", values between the minimum cutoff and a maximum cutoff (e.g., 0.01)
are reported in scientific notation, and p-values above the maximum cutoff are reported simply as, for example, 0.72.