[Halld-offline] decay chain genealogy scheme checked into trunk

[Mark Ito]

Folks,

As announced at the Offline Software Meeting, I checked in the decay 
chain scheme into the trunk yesterday as revision 12162. From the 
check-in comment:

o Introducing a new particle ID scheme.
o Older schemes are superceded.
o All parent ID's are filled in whenever parent particle received an ID. 
If not
    the parent ID set to -1.
o No Geant track numbers are used for particle IDs or parent IDs.
o Truth hits are associated with the new IDs.

All changes are in the src/programs/Simulation/HDGeant directory.

Since the change overwrites some old code having to do this this problem 
and was put in after the scons system was implemented, there was some 
hand merging to do. I think I got it right, but David: you should check 
that I didn't mess up the scons thing.

Kei: if you get a chance look at the new code, that would be great. Feel 
free to contact me if you see things that don't look right. Same goes 
for anyone else who is interested of course.

Note that this does not address all of the issues we have discussed. My 
hope is that we can turn to those now if necessary.

   -- Mark

-- 
Mark M. Ito, Jefferson Lab, (757)269-5295, marki at jlab.org