Allow running without tree by using

Allow running without tree by using
  clusterizer->SetDigitsArr(arr);
  clusterizer->SetOutput(0);
 and get resulting clusters using
  clusterizer->GetRecPoints()

Make flag to indicate that input is calibrated a member (it was static before)

Add void AliEMCALClusterizer::InitParameters(const AliEMCALRecParam* recParam) so that
one can pass a recParam object by hand. AliEMCALClusterizer::InitParameters() simply
returns InitParameters(AliEMCALReconstructor::GetRecParam());

General cleanup to improve readability of code.