Please add functions to convert between cl:pathname and iolib/pathnames

[knobo]

Subject says it all.

[sionescu]

It's probably straightforward to convert from IOlib pathnames to CL ones, but not the opposite because there are too many corner cases and features that are allowed to be implementation-specific, and which IOlib doesn't support.

If you do an analysis of a mapping between the two types of pathnames, I'm willing to write the code.