AliAnaPi0: Add possibility to cut on opening angle of pairs, to reject background...

AliAnaPi0: Add possibility to cut on opening angle of pairs, to reject background. Opening angle histograms added.

AliAnaCalorimeterQA:
 - Histograms to display cells energies for different fractions of the super modules
 - Histograms to calculate the measured time  of a cell in a cluster minus the time of cell with highest energy
 -Histogram to accumulate time measured in cells, fill grid of SuperModule. Only for cell energy larger than 0.5 GeV
- Corrected loop of invariant mass calculation, maximum index in second loop was wrongly set to one unit less.