Update to rough.js 4.0.1 (#363)

* upgrade to latest rough.js

* remove random.ts because roughjs now supports seeding.

src/random.ts

@@ -1,18 +0,0 @@
-// https://stackoverflow.com/questions/521295/seeding-the-random-number-generator-in-javascript/47593316#47593316
-export const LCG = (seed: number) => () =>
-  ((2 ** 31 - 1) & (seed = Math.imul(48271, seed))) / 2 ** 31;
-
-export function randomSeed() {
-  return Math.floor(Math.random() * 2 ** 31);
-}
-
-// Unfortunately, roughjs doesn't support a seed attribute (https://github.com/pshihn/rough/issues/27).
-// We can achieve the same result by overriding the Math.random function with a
-// pseudo random generator that supports a random seed and swapping it back after.
-export function withCustomMathRandom<T>(seed: number, cb: () => T): T {
-  const random = Math.random;
-  Math.random = LCG(seed);
-  const result = cb();
-  Math.random = random;
-  return result;
-}