WIP: First attempt at calling lb-run instead of SetupProject

Not functional but it adds an (undocumented) option: --lb-run That swaps the SetupProject call with a call to SP2. It's been done by changing sys.argv before calling SP2.script, am not happy about that.

Now we need to decide how we call lb-run. We can either call lb-run [...] LCG/version or LbScripts/version

Calling LbScripts means that we need to maintain a manifest.xml and xenv with LbScripts. I have a problem with tha solution, as we need to hardcode a platform on there with the <binary_tag> which I'm not happy about... What about local installation on ARM ?

We can otherwise call lb-run on LCG, and specifying that we need Python and pytools as externals (n.b. Pytools is disappearing in new releases). The drawback is that the LbScripts directories are not added to the path, but that's not a big deal as we can easily add the code to add them, based on LbLogin.py location.

Of course there is still the issue of how to decide on the LCG version...