refactoring code

Author: Hubert Koster

src/javascript/app/common/form_validation.js

@@ -160,9 +160,7 @@ const Validation = (() => {
     // ----- Validation Methods -----
     // ------------------------------
 
-    // The unicodes in the validEmail check, only select latin alphabet characters.
-    // This allows filtering other invalid unicode alphabet characters.
-    const validEmail        = value => /^(([a-zA-Z0-9\u0080-\u00ff\u0100-\u017f\u0180-\u024f][^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z0-9]+\.)+[a-zA-Z]{2,}))$/.test(value);
+    const validEmail        = value => /^(([a-zA-Z0-9][^!@£$%^&*=/?§±~<>(){}[\]\\.,;:\s@"'`]+(\.[^!@£$%^&*=/?§±~<>(){}[\]\\.,;:\s@"'`]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z0-9]+\.)+[a-zA-Z]{2,}))$/.test(value);
     const validRequired     = (value, options, field) => {
         if (value.length) return true;
         // else