Made parsers safe for situations where a given alias or taxonomy_id is used for more than one species, as is the case for oryza_sativa_japonica (alias oryza_sativa) and oryza_sativa_indica (alias oryza_sativa)

changed deprecated method plus changed fetch_by_band description to say do not use it as it makes no sense

  If there are no synonyms, return an empty list, not a list containing
  a reference to an empty list.

Performance optimisation in fetch_all_by_feature_class method. Contributed by Shiran Pasternak at CSHL