LONDON (Reuters) - They came, they saw, but sadly Britain's music critics largely failed to enjoy Tuesday night's revival of girl power at the world premiere of the Spice Girls' musical "Viva Forever!" Reviewers panned a production loosely based on the band's meteoric rise to fame in the 1990s, complaining that its "charmless" script failed even as a basic invention for folding nostalgic pop hits into a West End stage show. ...