Merge work on DG from Erlangen.
Fix the merge.
Temporarily suspend the new feature of calculating integration order of exact functions - to preserve test values.
A fix in error calculator.
Add DG examples.
Work on DG integration order calculation & related.
Make SimpleVector constructor allocate data.
Drop the -Ofast that is not present on older gcc (<4.6).
Add some overloads to mixins.
Update the export / import algebraic headers to be more user-friendly.
Fixes in MatrixRhsImportExport.
Fix in ExactSolutionEggShell.