Change a bunch of functions to use iterators
Make error messages show properly when getting certain computer failures

Also change them to use iterators
Convert most of construction.cpp to use iterators
Convert almost all of crafting.cpp to use iterators
Change some of creature_tracker.cpp to use iterators
Change parts of defense.cpp to use iterators
Change dependency_tree.cpp to use iterators
Change disease.cpp to use iterators
Change most of editmap.cpp to use iterators
Change faction.cpp to use iterators
Change field.cpp to use iterators