Concepts redesigned and FieldVector/FieldMatrix operations added

dune/amdis/Assembler.hpp

dune/amdis/DirichletBC.hpp

dune/amdis/FirstOrderAssembler.hpp

dune/amdis/Operator.hpp

dune/amdis/OperatorTermBase.hpp

dune/amdis/SecondOrderAssembler.hpp

dune/amdis/ZeroOrderAssembler.hpp

dune/amdis/common/Concepts.hpp

dune/amdis/common/ConceptsBase.hpp

dune/amdis/common/FieldMatVec.hpp

dune/amdis/common/Operations.hpp

dune/amdis/common/Traits.hpp

dune/amdis/terms/CoordsTerm.hpp

dune/amdis/terms/DOFVectorTerm.hpp

dune/amdis/terms/FunctorTerm.hpp

dune/amdis/terms/TermGenerator.hpp

dune/amdis/utility/GetEntity.hpp