allow to pass quadrature rule to makeOperator, cleanup of documentation

doc/doxygen/Doxylocal

dune/amdis/CreatorInterface.hpp

dune/amdis/GridFunctionOperator.hpp

dune/amdis/GridFunctions.hpp

dune/amdis/LocalAssembler.hpp

dune/amdis/Mesh.hpp

dune/amdis/Operations.hpp

dune/amdis/Operators.hpp

dune/amdis/assembler/FirstOrderDivTestvecTrial.hpp

dune/amdis/assembler/FirstOrderGradTestTrial.hpp

dune/amdis/assembler/FirstOrderGradTestTrialvec.hpp

dune/amdis/assembler/FirstOrderPartialTestTrial.hpp

dune/amdis/assembler/FirstOrderTestDivTrialvec.hpp

dune/amdis/assembler/FirstOrderTestGradTrial.hpp

dune/amdis/assembler/FirstOrderTestPartialTrial.hpp

dune/amdis/assembler/FirstOrderTestvecGradTrial.hpp

dune/amdis/assembler/SecondOrderDivTestvecDivTrialvec.hpp

dune/amdis/assembler/SecondOrderGradTestGradTrial.hpp

dune/amdis/assembler/SecondOrderPartialTestPartialTrial.hpp

dune/amdis/assembler/ZeroOrderTest.hpp