Move all implementations of spaces into a dedicated directory

CHANGELOG.md

dune/gfe/CMakeLists.txt

dune/gfe/cosseratenergystiffness.hh

dune/gfe/cosseratrodenergy.hh

dune/gfe/cosseratvtkreader.hh

dune/gfe/cosseratvtkwriter.hh

dune/gfe/geodesicfeassemblerwrapper.hh

dune/gfe/localgeodesicfefunction.hh

dune/gfe/localintegralenergy.hh

dune/gfe/localprojectedfefunction.hh

dune/gfe/localquickanddirtyfefunction.hh

dune/gfe/nonplanarcosseratshellenergy.hh

dune/gfe/polardecomposition.hh

dune/gfe/simofoxenergy.hh

dune/gfe/spaces/CMakeLists.txt

dune/gfe/spaces/hyperbolichalfspacepoint.hh

dune/gfe/spaces/orthogonalmatrix.hh

dune/gfe/spaces/productmanifold.hh

dune/gfe/spaces/quaternion.hh

dune/gfe/spaces/realtuple.hh