Add source map

Author: samuelmeuli

package.json

@@ -4,7 +4,7 @@
 "main": "lib/InputNumeric.js",
 "scripts": {
 "start": "run-p rollup storybook",
-"rollup": "rollup -c --watch",
+"rollup": "rollup -c --sourcemap --watch",
 "storybook": "start-storybook -p 6006",
 "build": "rollup -c",
 "lint": "eslint .",