Allow the items-node to have a list-value.

The items-node in the classes section now supports list values instead
of strictly string-values. This should make it easier to see exactly
which items a class has, and it should alleviate some of the problems
associated with apostrophes and such. The string-valued setup is still
supported to preserve some backwards compatibility.

The armor-node remains untouched, but it will probably be updated to
the same system later.