Renamed script to add Central AOD task from

Renamed script to add Central AOD task from
AddTaskCentral.C to AddTaskCentralMult.C  - to be
consistent.

Fixes for the event normalisation calculations.  We
can now properly use beta in the formula

  N = 1/E_T (N_A + N_A/N_V (N_T - N_V - beta))

Note, that this requires that the physics selection
does not check the that the hw trigger class is a
collision trigger.

Fixes for the TrainSetup.C script.

MakeAOD.C and MakedNdeta.C will now use TrainSetup.C
if libRAliEn.so is available and working.

Run.sh likewise will use the TrainSetup.C, unless
libRAliEn.so is not available (checked) or an empty
name is passed via the option -N.

DrawdNdeta.C fixed upd a little.

Note, to check for a true collision, one now needs to
do

   AliAODForwardMult::IsTriggerBits(kB|kNSD)

for example - otherwise you also get A, C, AC, and E
triggers that are also NSD off-line triggers.   This
is done automatically in

   AliAODForwardMult::CheckEvent