However, we're leaving the default at 1.25x for backwards compatibility, for now.
Also:
1. Actually use the configured replace fee ratio.
2. Store said ratios as percentages instead of floats. 1.25, or 1+1/(2^2),
can be represented as a float. 1.1, or 1 + 1/(2 * 5), cannot.
fixes#10415
