[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 thought the plan for this method was that it would never call out to the system at all -- it was just going to be a string processing routine. Here I see several system calls to get the cwd and drive letter.