Open Source Adventures: Episode 20: Imba 2 ROT-N

I want to start porting Imba 1 apps to Imba 2 with the simplest one - ROT-N decoder. Here's Imba 1 version. You either paste text into the box or use file upload, and then it decodes every ROT-N from ROT-1 to ROT-25. It's somewhat useful for elementa...