Chirp path bugfix

This pull request resolves issues with root path handling for Chirp. Chirp now always changes directory to "/" and so all paths accessed must be absolute. [As a general rule, daemon's should always operate in "/" so they do not prevent unmounting file systems.]

There is also a new path library for dttools that organizes functions that used to be in stringtools and adds some other useful functions.

Fixes #167.

@malbrec2 please look this over.