Feature/openmp
- output restricted to process 0 also in openmp mode
- some openMP cleanup
- interface cleanup
- constness of some functions added
- initfile singleton made thread-safe (at least the construction
- refinement-expressions corrected
- DOFSerializer added
- DOFSerializer implementation put into .cc file
- coupling-baseproblem made a base-problem
- added flag ENABLE_MPI to cmake
- small corrections in various files
- calcSignedDist for periodic boundary conditions
- Memory leak in SystemVector corrected
- Added cmake flags for openMP and MPI. Now, ENABLE_PARALLEL_DOMAIN requires ENABLE_MPI.