Add a way to timeout layout calls

[Eddykasp]

Programmers aren't perfect and neither are their programs. Layout using ELK can sometimes run into bugs that cause infinite loops (e.g. #993) and even if it is not an infinite loop in some cases layout might take far too long. For these situations it would be valuable to be able to add a timeout to the layout call that could be optionally set. Maybe simply via a property.