Use dummy TH1F to store PID setup values, make output mergable
Use dummy TH1F to store PID setup values, make output mergable

- With the old implementation using a TObjArray of TStrings, the output
  was not mergable and resulted and many warings in the automatic merging
  of the lego tain.
- This was fixed by using dummy TH1Fs and abusing the x-Axis lables.
- ALIROOT-5623
- ALIROOT-5976

alisw/AliRoot,sebaleh/AliRoot,jgrosseo/AliRoot,ALICEHLT/AliRoot,alisw/AliRoot,sebaleh/AliRoot,ecalvovi/AliRoot,miranov25/AliRoot,mkrzewic/AliRoot,shahor02/AliRoot,jgrosseo/AliRoot,coppedis/AliRoot,miranov25/AliRoot,mkrzewic/AliRoot,alisw/AliRoot,shahor02/AliRoot,alisw/AliRoot,sebaleh/AliRoot,miranov25/AliRoot,sebaleh/AliRoot,ecalvovi/AliRoot,ALICEHLT/AliRoot,ecalvovi/AliRoot,alisw/AliRoot,ALICEHLT/AliRoot,miranov25/AliRoot,coppedis/AliRoot,sebaleh/AliRoot,alisw/AliRoot,mkrzewic/AliRoot,jgrosseo/AliRoot,shahor02/AliRoot,alisw/AliRoot,coppedis/AliRoot,jgrosseo/AliRoot,jgrosseo/AliRoot,alisw/AliRoot,ecalvovi/AliRoot,ecalvovi/AliRoot,ALICEHLT/AliRoot,mkrzewic/AliRoot,miranov25/AliRoot,ALICEHLT/AliRoot,mkrzewic/AliRoot,miranov25/AliRoot,shahor02/AliRoot,sebaleh/AliRoot,mkrzewic/AliRoot,mkrzewic/AliRoot,miranov25/AliRoot,jgrosseo/AliRoot,jgrosseo/AliRoot,coppedis/AliRoot,miranov25/AliRoot,shahor02/AliRoot,coppedis/AliRoot,ecalvovi/AliRoot,ALICEHLT/AliRoot,ALICEHLT/AliRoot,coppedis/AliRoot,coppedis/AliRoot,coppedis/AliRoot,shahor02/AliRoot,shahor02/AliRoot,sebaleh/AliRoot,ecalvovi/AliRoot