Feature/data transfer implementation

src/amdis/DataTransfer.hpp

src/amdis/DataTransfer.inc.hpp

src/amdis/common/Apply.hpp

src/amdis/utility/TreeContainer.hpp

test/CMakeLists.txt

test/DOFVectorTest.cpp

test/DataTransferTest.hpp

test/DataTransferTest2d.cpp

test/DataTransferTest3d.cpp

test/DiscreteFunctionTest.cpp