Sašo Živanović

Implement and document pgfkeys tracing.

2

**Motivation for this change** In 2012, Ryan Reich wrote a handy little utility for tracing the execution of pgfkeys processing. However, his unpublished `trace-pgfkeys.sty` had a form of a runtime...

`file("c:foo.txt")` loses the volume, i.e. it becomes `foo.txt` relative to the current directory, not the current directory on drive C. Incidentally, `dir("c:foo.dir")` works as expected.