use usage approach for less bloat

Author: outofambit

package.json

@@ -112,7 +112,7 @@
       [
         "@babel/preset-env",
         {
-          "useBuiltIns": "entry",
+          "useBuiltIns": "usage",
           "corejs": 3
         }
       ]

src/app.js

@@ -1,6 +1,3 @@
-// polyfills for compatibility with older browsers
-import 'core-js';
-
 // core
 import p5 from './core/main';
 import './core/constants';