
---- Modify v01 and introduce classes ----

Replace the struct "Event" with a class "Event" and 
the functions "add" and "stat" with a class "BraggStatistic", as 
described in the following.

***
Create a class "Event" with:
- the event identifier,
- the number of points,
- the array of energies,
- two "static" members with the min and max number of points.
Add to the class:
- a constructor taking the event-id as parameter,
- a destructor,
- a function "add" to append a point energy, taken as argument,
- a function "dataSize" returning the number of points,
- a function "energy" taking an int as argument and returning the energy 
  at the corresponding point.
Create and delete the array of energies in the contructor and destructor,
using the max number of points as size.
In the function "add" check if the max number of points has been reached, 
if not append the new energy and increase the number of points.

***
Create a class "BraggStatistic" with:
- two numbers for min and max total energy
- the number of selected events
- two arrays for sum of energies and squares for all points
- two arrays for mean and rms energies for all points
Add to the class:
- a constructor taking the min and max energies as parameters,
- a destructor,
- a function "add" taking as argument a reference to const-Event,
  to update the sum of energies and squares,
- a function "compute" to compute mean and rms energies.
- a function "nEvents" returning the number of selected events,
- two functions "eMean" and "eRMS" returning the pointers to the 
  arrays of mean and rms energies,
Create and delete all the arrays in the contructor and destructor,
using the min number of points as size.
In the function "add" check if the total energy is in the required range, 
if yes increase the sums.

***
In the "main" function create 4 instances of "BraggStatistic", to select 
events with total energies in the ranges:
background : min = 3000 , max = 5000
africium   : min = 6000 , max = 6499
asium      : min = 6500 , max = 6799
australium : min = 6800 , max = 7200

********* final list of functions *********

main                   to complete
read                   to complete
dump                   modify Mean_v01

********* final list of classes   *********

                       .h                            .cc
Event                  to complete                   to complete
BraggStatistic         to complete                   to complete
