quattor/CAF — pull request #12 by stdweird (2014-03-20 08:26:40+00:00)
Title: Expose seek offset to add_or_replace_lines

Expose the ```IO::String::seek``` whence and offset to ```add_or_replace_lines```. This will make it possible to ```add``` in arbitrary locations.
Also provide some utility functions to help determine the add position.