By Kevin Maguire Supertato sounded like a bag of stale crisps or another takeaway selling tasteless grub until my grandson opened my eyes to a brave new world. Meet a wholesome figure in a black mask and belt with red cape fighting selflessly to make life better for everybody. That’s Supertato, not my grandkid, although I do hope Little L grows up to be a model citizen caring for others, liking football and drinking real ale. The world’s first potato superhero would have been off my radar if I hadn’t been babysitting. After all, adults watching CBeebies all alone is, well, a bit creepy. My str…