More changes as a consequence of changing the pad geomtry in the new

More changes as a consequence of changing the pad geomtry in the new
AliROOT. Some hardcoded values which were set to 176 has now been changed
to AliL3Transform::GetNRows() etc. Also the remaining hardcoded AliTPCParam
and digits tree object names has been changed in AliL3FileHandler.
There were and still are a bug in the AliL3Merger class in FillNTuppel,
which I was not able to figure out, so I switched off. This only affects
the SlowMerging methods in the track mergers, and should be looked at more
if needed in the future.