Begin linear solver interface

CMakeLists.txt

src/CMakeLists.txt

src/algebra/CMakeLists.txt

src/algebra/LinearSystemSolver.cpp

src/algebra/LinearSystemSolver.hpp

src/algebra/PETScWrapper.cpp

src/algebra/PETScWrapper.hpp

src/algebra/SparseMatrixDescriptor.hpp

src/utils/BuildInfo.cpp

src/utils/BuildInfo.hpp

src/utils/PugsUtils.cpp

src/utils/pugs_config.hpp.in

tests/CMakeLists.txt