a side effect of the stack loop already - replace all backslashes by slashes, to avoid security problems on UNIX (if support for them is desirable on MS Windows, then we'd need an OS property)
mf: fixpath(): function to normalize file paths (doesn't handle escaped characters yet)
stuff is, for the most part, already available in the geo module; but it's small and this naming matches the evolvoing "standard nasal library".