[Whitespace] Clean up whitespace in gridoperator/common/CMakeLists.txt
[Bugfix][CMake] Distribute all files in gridoperator/common
[Bugfix][Buildsystem] Distribute diagonallocamatrix.hh in gridoperator/common

Looks like I forgot to add that file to both build systems. Fixed.
[Whitespace] Clean up whitespace in gridoperator/common/CMakeLists.txt
[Bugfix][Buildsystems] Install pkqkfem.hh and qkdggl.hh
[Bugfix][CMake] Add missing header files to CMakeLists.txt