Clean up solver structure and made class GaussAlgorithm a class template.
- Removed several useless classes (
LinearSolver
,DirectLinearSolver
andDenseDirectLinearSolver
) and in the consequence the inheritance structure of solvers. - Class
GaussAlgorithm
is now a template class. The template arguments are matrix type and vector type. For new matrix and/or vector types it is necessary to specialize the template. This is already done for vector typedouble*
.