CmdLine: show a better version than 0.0.0.0

This takes the result of our long version (eg: v1.1.3-29-g749a11f) and
munges it into a C# compatible x.x.x.x string (eg: 1.1.3.29).

This is only really shown on the help screen, but it no longer looks
*weird* on the help screen. :)

Closes #362.