Cleanup

Remove a bunch of outdated things:

• Old code dealing with instrumental missing p_T, including InstrMetAnalysis. It's not used after !115 (merged).
• MainAnalysis. It was only needed for instrumental missing p_T.
• launchAnalysis.sh and old scripts for plotting and datacards. After !115 (merged), launchAnalysis.sh is not used even for instrumental missing p_T.
• MelaWeight. It won't be useful for the computation of MELA weights on the fly.
• Unused things in Utils.h/Utils.cc.

@npostiau I assumed that the remaining scripts in Tools and WeightsAndDatadriven are still in use. Let me know if some of them should also be deleted.