Fix substitution of i-ogonek and upper combining marks.

Fix broken cup (`∪`) and cap (`∩`) symbol
Fix Fix broken degree-C and degree-F ligature.
Closes #449, #450.

support/curve-util.js

@@ -0,0 +1,66 @@
+"use strict";
+
+const quadify = require("primitive-quadify-off-curves");
+
+exports.OffsetCurve = class OffsetCurve {
+	constructor(bone, offset, contrast) {
+		this.bone = bone;
+		this.offset = offset;
+		this.contrast = contrast;
+	}
+	eval(t) {
+		const c = this.bone.eval(t);
+		const d = this.bone.derivative(t);
+		const absD = Math.hypot(d.x, d.y);
+		return {
+			x: c.x - (d.y / absD) * this.offset * this.contrast,
+			y: c.y + (d.x / absD) * this.offset
+		};
+	}
+	derivative(t) {
+		const DELTA = 1 / 0x10000;
+		const forward = this.eval(t + DELTA);
+		const backward = this.eval(t - DELTA);
+		return {
+			x: (forward.x - backward.x) / (2 * DELTA),
+			y: (forward.y - backward.y) / (2 * DELTA)
+		};
+	}
+};
+
+exports.curveToContour = function(curve, err) {
+	let exitPoints = [];
+	const z0 = curve.eval(0);
+	const z1 = curve.eval(1);
+	exitPoints.push({
+		x: z0.x,
+		y: z0.y,
+		cubic: false,
+		on: true
+	});
+	const offPoints = quadify.autoQuadify(curve, err || 1);
+	for (let k = 0; k < offPoints.length; k++) {
+		const z = offPoints[k];
+		if (k > 0) {
+			const z0 = offPoints[k - 1];
+			exitPoints.push({
+				x: (z.x + z0.x) / 2,
+				y: (z.y + z0.y) / 2,
+				on: true
+			});
+		}
+		exitPoints.push({
+			x: z.x,
+			y: z.y,
+			cubic: false,
+			on: false
+		});
+	}
+	exitPoints.push({
+		x: z1.x,
+		y: z1.y,
+		cubic: false,
+		on: true
+	});
+	return exitPoints;
+};