[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 don't think this phrase makes sense. It is especially confusing since the shell uses "path" as the name of the environment variable that has a list of directories for searching, while you are using it here as short for pathname. Also shell doesn't mean the same thing to unix and windows users. Many things go on in a shell, including lots of ways of dealing with files. You should just say explicitly what happens if swd is an empty string.

Also the confusion between "path" (variable) and "pathname" makes me think you should not abbreviate here but always use "pathname" unless you mean search path.