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

@@ -65,7 +65,7 @@
 
 // grid dimension
 const int dim = 2;
-const int dimworld = 3;
+const int dimworld = 2;
 
 // Order of the approximation space for the displacement
 const int displacementOrder = 2;