...and use that info if no version and/or interface age was specified. This
way, we can use this script to help bootstrap builds from Visual Studio
projects directly from a GIT checkout.
Rename the script as gen-version-items.py, and so make things more generic and
usable by other items in the build. We want to eventually to be able to
generate the .rc files and the *version*.h files from their *.in counterparts
using this script.