FIX Quater.inl in the computation of the euler angles (again).
FIX Quater.inl in the computation of the euler angles (again).

Add a line to avoid singularities in the calculation.
Convert comments to doxygen comments.


Former-commit-id: c527d11678d9afacd19cdc7c7fc42f0a28849ed1
Anatoscope/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,Anatoscope/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,hdeling/sofa,Anatoscope/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,FabienPean/sofa,FabienPean/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa,FabienPean/sofa,Anatoscope/sofa,hdeling/sofa