ref: 4bb9232bcb2a8d5c7e43e54136f839df142e6204
parent: c696ee2220a89d30b109f4d3d95ca36cfc44fff0
author: Simon Tatham <anakin@pobox.com>
date: Wed Apr 29 19:11:10 EDT 2009
check_valid() wasn't checking that Killer cages contain at most one of each digit, and - perhaps more importantly - the display code wasn't highlighting violations of that rule as an error. Fix both. [originally from svn r8540]