[WIP] deconstructPathRelativeToSWD

Addresses fixes to deconstructPathname (addresses issue #264). Introduces a new function deconstructPathRelativeToSWD that finds the absolute path to a given path name relative to a specified working directory (swd).
I think "absolute path" is a good term but it needs to be defined. How about something like "by absolute path we mean a root-relative path name, and on Windows it will begin with an explicit drive letter." The term "full absolute path" doesn't have a well known meaning anyway so would also require a definition.