fhi_aims: added metadata for parsing of the band structure

remove starting_point_method_ref and starting _point_calculation_ref and
replace them with section_method_to_method_refs and
section_calculation_to_calculation_refs that allow external references
and annotated references (not only starting point, but also qm_1 mm_1 and
similar for QM/MM methods...

try to use source_to_target_ref dropping the section part as name for
references as much as possible (i.e. unless some that wold not give
the intent well)

Sections added in section_run:

 * section_topology
   * section_atom_type
   * section_molecule_type
     * section_molecule_constraint
     * section_molecule_interaction
   * section_constraint
   * section_interaction
 * section_sampling_method
 * section_frame_sequence
   * section_frame_sequence_user_quantity

fhi_aims: extended metadata to convergence of geometry optimizations

fhi_aims: added metadata to indicate convergence