[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 you want to use `getPathSeparatorChar()` here, because that will return `\` (backslash) on Windows, but you just turned all the slashes into forward slashes temporarily. So the last character won't ever match a backslash.