feat: Allow reconfiguration of an existing picomath instance

Keeps track of which operations depend on the configuration and
  invalidates them for lazy reconfiguration when the config changes.

complex/add.js

@@ -13,6 +13,7 @@ export default function create(pmath) {
            }
            if (resolve && Math.abs(sum.im/sum.re) < 1e-10) return sum.re
            return sum
-       }])
+       }],
+    create, pmath) // register ourselves for invalidation and reconfiguration
 }