Add fetch_all_by_GOTerm():

  Arg [1]   : Bio::EnsEMBL::OntologyTerm
              The GO term for which genes should be fetched.

  Example:  @genes = @{
              $gene_adaptor->fetch_all_by_GOTerm(
                $go_adaptor->fetch_by_accession('GO:0030326') ) };

  Description   : Retrieves a list of genes that are associated with
                  the given GO term, or with any of its descendent
                  GO terms.  The genes returned are in their native
                  coordinate system, i.e. in the coordinate system
                  in which they are stored in the database.  If
                  another coordinate system is required then the
                  Gene::transfer or Gene::transform method can be
                  used.

  Return type   : listref of Bio::EnsEMBL::Gene


(similarly for TranscriptAdaptor and TranslationAdaptor)