Add choice of solution strategies to simulators.

The following is changed in this commit:
 - The constructor for NewtonIterationBlackoilSimple now takes
   a parameter object instead of a linear solver.
 - The fully implicit black-oil simulators can now use the CPR
   preconditioning strategy (by passing use_cpr=true) or the
   simple strategy (the default).
Note that as of this commit, the CPR preconditioning still has
not been implemented properly, and behaves just like the simple
strategy.

examples/test_implicit_ad.cpp

@@ -102,8 +102,7 @@ try
     double grav[] = { 0.0, 0.0 };
     Opm::DerivedGeology geo(*g, props, grav);
 
-    Opm::LinearSolverFactory linsolver(param);
-    Opm::NewtonIterationBlackoilSimple fis_solver(linsolver);
+    Opm::NewtonIterationBlackoilSimple fis_solver(param);
 
     Opm::FullyImplicitBlackoilSolver<UnstructuredGrid> solver(*g, props, geo, 0, *wells, fis_solver);