/*! @page mainfile LEmuSR Tree

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@section smainfile The main file: LEMuSR.cc

 
The main file of the simulation is LEMuSR.cc. It initializes the main classes. 
Those are the initialization classes and the action classes. They are hierarchized in two categories:
<ul>
<li> the mandatory classes, which <b>must</b> be implemented for any simulation. They define the geometry, the physics interactions and the initial state of the particles to simulate.
<li> the optionnal classes, which are not necessary to get a simulation running. They define optionnal parameters for the visualization or the user interaction, but also specific actions the user wants to perform during the simulation, like histogramming or events sorting.
</ul>


The very first component of the simulation is the <b>run manager</b>. It is an object of the class G4RunManager and has to be instanciated at the beginning of the main file. As stated by the name, its role is to manage the simulation. In LEMuSR.cc, the user feeds the run manager with all the different @ref mandatory and @ref optionnal classes.

*/