Allow the up/down cursor keys to wrap to the top or bottom of the list.

I find it useful to allow the up/down cursor keys to wrap around the OakFilterList. Anyone else have a use for it? Please consider this patch public domain.

![textmate_file_cursor_wrap](https://f.cloud.github.com/assets/6807/1489069/b6509a24-4763-11e3-8f0a-1c162a4cffb3.gif)