Cosserat-Continuum-Nonplanar

@osander: Can you have a look here?

This MR cleans up the usage of MIXED_SPACE in cosserat-continuum.

Now all combinations of dim = dimworld or dim != dimworld and MIXED_SPACE = 0 or MIXED_SPACE = 1 at least compile.

Also, this MR points out the one combination that still can't be solved: Problems with dim != dimworld do not work for MIXED_SPACE = 1!

As soon as I need this for locking tests I will add this; I will have to change Nonplanarcosseratshellenergy so it can be assembled with the GFEMixedAssembler.

src/cosserat-continuum.cc

@@ -63,7 +63,7 @@
 #endif
 
 #ifndef WORLD_DIM
-#  define WORLD_DIM 3
+#  define WORLD_DIM 2   
 #endif
 const int dimworld = WORLD_DIM;
 
@@ -572,6 +572,9 @@ int main (int argc, char *argv[]) try
                 solver.solve();
                 xRBM = solver.getSol();
             } else { //parameterSet.get<std::string>("solvertype") == "cholmod"
+#if DUNE_VERSION_LT(DUNE_COMMON, 2, 8)
+                DUNE_THROW(Exception, "Please install dune-solvers >= 2.8 to use the Proximal Newton Solver with Cholmod!");
+#else
                 RiemannianProximalNewtonSolver<DeformationFEBasis, RBM> solver;
                 solver.setup(*grid,
                              &assembler,
@@ -584,6 +587,7 @@ int main (int argc, char *argv[]) try
                 solver.setInitialIterate(xRBM);
                 solver.solve();
                 xRBM = solver.getSol();
+#endif
             }
 
             for (int i = 0; i < xRBM.size(); i++) {