comparing bmesh to trunk, mesh_calc_normals() in bmesh is a much more comprehensive function, calculating mpoly,mface normals, where trunk only calculated vertex normals. renamed: * mesh_calc_normals() --> mesh_calc_normals_mapping_ex * mesh_calc_tessface_normals --> mesh_calc_normals_tessface() - only calculates normals from tessface * added mesh_calc_normals() - only calculates normals from poltys this way we can have mesh_calc_normals() remain fast for parts of the code which only need vertex normals to be updated. only refactor, no func changes- didnt replace mesh_calc_normals_mapping_ex() with mesh_calc_normals() anywhere yet.