Issue #7: Refactor input validation code

When pasting content directly from a spreadsheet where the separator is \t, all lines are marked as invalid because of this separator

guids-generator.html

@@ -284,7 +284,7 @@
                 if (!line) continue;
 
                 let info = line.trim()
-                             .split(',')
+                             .split(/[\t,]+/)
                              .map( (item) => (item.trim()) )
                              .filter( (item) => (item) );