[Feature Request] Specify location of done.txt, report.txt

[lamyergeier]

Todo.txt gives us flexibility to configure (in config file) separate location for todo.txt, done.txt and report.txt. This is useful, as I create a folder Todo and Done and keep these files separately in these folders as I have other documents relating to task in these folders as well.

Please let us choose the location of done.txt, report.txt as I would not want it to be the same as todo.txt