rewritten mesh creator to support more general creation

examples/cahn_hilliard.cc

examples/init/heat.dat.2d

examples/init/stokes.dat.2d

src/amdis/BoundaryManager.hpp

src/amdis/CMakeLists.txt

src/amdis/Mesh.hpp

src/amdis/MeshCreator.hpp

src/amdis/ProblemStat.hpp

src/amdis/ProblemStat.inc.hpp

src/amdis/common/Concepts.hpp

src/amdis/utility/CMakeLists.txt

src/amdis/utility/MacroGridFactory.hpp

test/MarkerTest.cpp