Added fmt as output formatting library

CMakeLists.txt

LICENSE

dune.module

examples/CMakeLists.txt

examples/ellipt.cc

externals/CMakeLists.txt

src/CMakeLists.txt

src/amdis/AdaptInstationary.cpp

src/amdis/Assembler.inc.hpp

src/amdis/CreatorMap.hpp

src/amdis/FileWriter.hpp

src/amdis/InitfileParser.cpp

src/amdis/Marker.inc.hpp

src/amdis/Mesh.hpp

src/amdis/Output.hpp

src/amdis/ProblemStat.hpp

src/amdis/ProblemStat.inc.hpp

src/amdis/StandardProblemIteration.cpp

src/amdis/linear_algebra/LinearSolver.hpp

src/amdis/linear_algebra/istl/DOFMatrix.hpp