Restructure to compile files seperately

• make gemver will compile and run the evaluate_gemver.cpp file with g++
• make gemver_mpi will compile run the evaluate_gemver_mpi.cpp file with mpicxx
• similarly make test_gemver and make test_gemver_mpi for testing

1. Does this structure make sense? Or should there be one evaluate.cpp and one evaluate_mpi.cpp and not one each for gemver/trisolve?
2. Should we include the data initialization in our timing or not?