Clean and add convergence parameters to CGSolver.

src/libintegratorSparse/centralDifferencesSparse.cpp

src/libintegratorSparse/centralDifferencesSparse.h

src/libintegratorSparse/eulerSparse.cpp

src/libintegratorSparse/eulerSparse.h

src/libintegratorSparse/implicitBackwardEulerSparse.cpp

src/libintegratorSparse/implicitNewmarkSparse.cpp

src/libintegratorSparse/implicitNewmarkSparse.h

src/libintegratorSparse/integratorBaseSparse.cpp

src/libintegratorSparse/integratorBaseSparse.h

src/libsparseSolver/CGSolver.cpp

src/libsparseSolver/CGSolver.h