Fixing ISsue #100

Issue was : doc in nextEdge for parameters nb_a1 and nb_a2 code: why functions less lessOrEqual equal ? It is better to use operators ? 

 - nextEdge doc was corrected.
 - the use of functions 'less' and 'lessOrEqual' is justified, I added a precisions on that point in the classe's documentation.
 - Code is unchanged, the only difference is some corrections of the indentation.