remove unused functions

- remove Variables.get_names(), .get_nodes_of_global_dofs()
  Variable.is_non_state_field(), FieldVariable.get_global_node_tab()
update setting of variables data (use Variable.set_data())

- remove Variables.data_from_state()
- update Variables.set_data()
- rename/update Variables.non_state_data_from_state() -> .set_data_from_state()
- remove Variable.data_from_state(), .data_from_data()
- rename/update Variable.data_from_any() -> .set_data()
- rename FieldVariable.data_from_qp() -> .set_data_from_qp()
- update all depending code
fix ANSYSCDBMeshIO.read(), guess it with .inp suffix

- new .guess()
- for mixed element meshes and coordinates without "solid" keyword