Command line parsing

Now allows:

$ GoldenCheetah [[directory] athlete]
$ GoldenCheetah [--version|--help]
$ GoldenCheetah

Passing the athlete on its own is as before, but you can
now also pass the folder name in as well.

I've also added the option to get a help message if you
pass --version or --help.

Lastly, as before, with no command line paramaters you
open the last athlete worked on.

Since we now output the version and build info I have uplifted
the build and version numbers in GcUpgrade.h to reflect the fact
we are now developing v3.1.