feat: Index behaviors by return typing strategy

* Adds the concept of, and options for, the return typing strategy
  * adds the strategy at the beginning of every behavior index
  * adds the strategy as an additional argument to resolve
  * No actual use of return type strategy so far
  * Sets up eslint
  * Fixes eslint errors

src/complex/Complex.js

@@ -11,7 +11,7 @@ function complexSpecialize(ComponentType) {
    const typeName = `Complex(${ComponentType})`
    if (ComponentType.concrete) {
       const fromSpec = [match(
-         ComponentType, math => r => ({re: r, im: ComponentType.zero}))]
+         ComponentType, () => r => ({re: r, im: ComponentType.zero}))]
       for (const {pattern, does} of ComponentType.from) {
          fromSpec.push(match(
             this.specialize(pattern.type),