Fix reciprocal minor tick spacing; bump to 0.84

Minor ticks on 1/x scales were using linear value interpolation between
harmonically-spaced major ticks. Because 1/v is highly convex, equal value
steps near a large major-value (left side of the first interval) map to tiny
physical steps, piling all ticks against the left wall. At a 1:1000 ratio the
first four minor ticks land at 0%/0%/1%/2% of the interval.

Fix: interpolate in position space (uniform physical spacing) for all
reciprocal intervals, matching how major ticks are laid out (also equal
physical steps) and matching the already-correct ∞-first-interval handling.

Also documents 1/x scale and ∞ max in README.

README.md

@@ -65,8 +65,9 @@ Calculated numbers are rendered in fixed-point notation at 4 significant figures
 | Linear | Evenly spaced | Uniform | None |
 | √ | Quadratic (0, 1, 4, 9 … × max) — compresses low values | Crowded toward the low end of each interval | Min ≥ 0 |
 | Log | Geometric (min × r⁰, r¹, r² …) — each interval spans the same ratio | Crowded toward the high end of each interval | Min and Max > 0 |
+| 1/x | Harmonic (values decrease left → right, e.g. ∞, 10, 5, 2, 1) — compresses high values | Uniform (in position space, i.e. proportional to 1/v) | Min and Max > 0; Max may be ∞ |
 
-The √ mapping is typical for AC RMS current and power meters, where needle deflection is proportional to the square of the measured quantity.
+The √ mapping is typical for AC RMS current and power meters, where needle deflection is proportional to the square of the measured quantity. The 1/x mapping is used for ohms/resistance scales, where values decrease from left (high resistance / ∞) to right (low resistance).
 
 ### Unit markup