/*! 
\page userapi User API

Here is a list of classes grouped in several categories to create the sample, describe scattering geometry, run the simulation and perform fitting.

<ul>
<li> \ref simulation "Simulation" <BR>
List of classes to describe beam, detector and run the simulation
<li> \ref samples "Samples" <BR> 
List of classes to describe scattering sample
<li> \ref materials "Materials" <BR>
Classes to describe magnetic and non-magnetic materials
<li> \ref formfactors "Form factors" <BR> 
List of form factors available
<li> \ref interference "Interference functions" <BR> 
List of implemented interference functions
<li> \ref algorithms "Algorithms and functions" <BR> 
Additional routines
<li> \ref tools "Tools" <BR> 
Different tools mainly to deal with intensity data
<li> \ref input_output "Input and output" <BR> 
Various routines to write intensity data on disk and to import user data.
<li> \ref fitting "Fitting" <BR> 
Fitting routines
</ul>
<BR>

Here is a list of additional classes from internal API.
<ul>
<li> \ref simulation_internal "Simulation (internal)" <BR>
<li> \ref samples_internal "Samples (internal)" <BR> 
<li> \ref materials_internal "Materials (internal)" <BR>
<li> \ref formfactors_internal "Form factors (internal)" <BR> 
<li> \ref interference_internal "Interference functions (internal)" 
<li> \ref algorithms_internal "Algorithms (internal)" <BR> 
<li> \ref tools_internal "Tools (internal)" <BR> 
<li> \ref input_output_internal "Input/output (internal)" <BR> 
<li> \ref fitting_internal "Fitting (internal)" <BR> 
</ul>




*/