Merge branch 'feature/organize-traits' into 'master'

dune/matrix-vector/CMakeLists.txt

dune/matrix-vector/algorithm.hh

dune/matrix-vector/axpy.hh

dune/matrix-vector/axy.hh

dune/matrix-vector/genericvectortools.hh

dune/matrix-vector/matrixtraits.hh

dune/matrix-vector/resize.hh

dune/matrix-vector/scalartraits.hh

dune/matrix-vector/test/resizetest.cc

dune/matrix-vector/traits/CMakeLists.txt

dune/matrix-vector/traits/fieldtraits.hh

dune/matrix-vector/traits/matrixtraits.hh

dune/matrix-vector/traits/scalartraits.hh

dune/matrix-vector/traits/utilities.hh

dune/matrix-vector/traits/vectortraits.hh

dune/matrix-vector/transformmatrix.hh