Update to use rollup.js

Thanks @ljmerza!

tsconfig.json

@@ -1,13 +1,10 @@
 {
   "compilerOptions": {
-    "jsx": "react",
-    "jsxFactory": "h",
     "target": "es2017",
     "module": "esnext",
     "moduleResolution": "node",
     "lib": ["es2017", "dom", "dom.iterable"],
     "noEmit": true,
-    "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noImplicitReturns": true,
     "noFallthroughCasesInSwitch": true,
@@ -17,4 +14,4 @@
     "resolveJsonModule": true,
     "experimentalDecorators": true
   }
-}
+}