List

Update of https://github.com/elkarte/Elkarte/pull/422 .. First step in moving this very used function to a class so it can be (in the future) extended etc ... Original text of commit below

> List class for discussion: I actually didn't make any changes (at all), only converted list to a class. For the >  clients, the same call is used, createList($param).
Client code can optionally also create a List object.

> I'd submit it so that we see it, know it exists, and eventually work it out better internally or externally: for example, we can factor it with an internal structure (instance variables from those parameters), and we can create subclasses to override the buildList() method.