Update verbose mode of SVDTJ (clearer msg on error + U/V tag of eigtj factor).

src/algorithm/factorization/faust_GivensFGFTGen.h

src/algorithm/factorization/faust_GivensFGFTGen.hpp

src/algorithm/factorization/faust_SVDTJ.cpp.in

src/algorithm/factorization/faust_SVDTJ.hpp