Add "tail" feature when viewing large working copy files.

If you click on a file in the working copy list, it's contents are sent to your browser. For text files, the file contents are displayed. If the file is large, it takes a long time to load, depending on the network speed. Often all you want to see is the end of the file.

It might be useful to be able to just get the last X lines of the file. Maybe you get to select X. Maybe it should be a fixed number of lines OR a fixed number of bytes (rounded to the next line break.