Release version 2.1.1

Author: c-w

package.json

@@ -42,7 +42,7 @@
     "type": "git",
     "url": "https://github.com/c-w/mathquill4quill"
   },
-  "version": "2.1.0",
+  "version": "2.1.1",
   "files": [
     "build/mathquill4quill.min.css",
     "build/mathquill4quill.min.js",