To generate  collisions at a given energy and write result to stdout so
that they can be an input to the primary file to Epics. (file name should
start with +).  Also you can generate a kind of trace files to visualize
particle tracks at each collision.  (Use geomview).

If you use an interaction model other than dpmjet, 
you may directly go to the section of how to prepare the
param file.  For dpmjet, you have to read the next section.

1)  preparation of files for dpmjet.
We distingush  projectile and target for the collision.
Collision generation is performed at the rest system of
the target and the resultant particle information is
boosted into the original system.  
a) For proton-target collisions, 
    cp protonTarget.inp  dpmjet.inp
b) If  heavy ion is involved,
    cp FeN.inp  dpmjet.inp

Then,  edit the dpmjet.inp:  adjust the
    ENERGY to be consistent with param file
The energy there is the projectile energy/nucleon
(or particle for non-heavy ion) (in GeV) at the
target rest system. 
To get that energy, it will be better to read
param file and see UserHooki.


2) Read param file.
3) ./make.csh to compile
4) ./Gencol...  < param > +somefile
