NOTICE: USE THIS PLUGIN ONLY FOR DATA THAT CONTAINS EVENTS WITH
        IDENTICAL EVENT TOPOLOGY!
        Reason: see below.

1) analyze an hddm data file "foo" like this:
   hd_ana --plugin=trackanal foo

   this will create an output file "trackanal.root"
   containing a root tree called "TrackTree"

2) ceate histograms from this file using code provided in src 
   like this:
   src/check2

   this will create output file called "histograms_trackanal.root"

3) run the root sript script ".x readhist.C" in root
   now you have hist[X] 1D histogrms and hist2d[X] 2D histograms

   the first 4 histrograms hist[0] to hist[3] are
   hist[0]: number of generated particles per event
   hist[1]: number of generated charged particles per event
   hist[2]: number of track candidates per event
   hist[3]: number of hits for each track candidate

   hist[4]:    number of hits for tracks where the majority of hits
               come from other particles than the thrown ones. 
   hist[4+i]   for each charged thrown particle i=1,..X
               the number of hits for each track candidate
               where the majority of hits belong to this track

   hist[4+1N+i] for each thrown particle the reconstructed momentum
                 devided by the thrown momentum for good track candidates

   hist[4+2N+i] PID not applicable at the moment

   hist[4+3N+i] percentage of hits belonging to thrown track i for
                track candidate that have the major hits from this track i

   hist[4+4N+i] number of track candidate per event where the majority of
                hits come from the thrown track i