Human-readable time periods in SCORM reports

Currently SCORM reports exhibit time periods notation format, which is understandable but yet not so user-friendly: P1DT1H2M32.1S for example. Using some complex regular expressions, we can replace this notation by usual one: 1 day 1 hour 2 minutes 32.1 sec. The attached patch does this by adding a formatter function and calling it in every place where report prints out date/time periods. The patch is applied with -p0.