LONDON — Royal images have been manipulated since at least the 1590s when artists painted Queen Elizabeth I as a young woman despite her being more than 60 years old.But the edited photo of Kate, the Princess of Wales, and her three children has stirred up a decidedly modern controversy as it has inflamed conspiracy theories about her whereabouts, while raising questions about the royal family’s role in constructing its own image and how, or whether, it can be trusted to do so. After the revelations that the photo to mark Mother’s Day in Britain — the first public depiction of…