added methods: calc_link_sum, calc_node_count, calc_leaf_count
added methods: calc_link_sum, calc_node_count, calc_leaf_count

kumarsaurabh20/ensembl-compara,danstaines/ensembl-compara,etapanari/ensembl-compara,Ensembl/ensembl-compara,etapanari/ensembl-compara,ckongEbi/ensembl-compara,kumarsaurabh20/ensembl-compara,Ensembl/ensembl-compara,dbolser-ebi/ensembl-compara,dbolser-ebi/ensembl-compara,Ensembl/ensembl-compara,kumarsaurabh20/ensembl-compara,Ensembl/ensembl-compara,danstaines/ensembl-compara,ckongEbi/ensembl-compara,danstaines/ensembl-compara,danstaines/ensembl-compara,dbolser-ebi/ensembl-compara,danstaines/ensembl-compara,etapanari/ensembl-compara,Ensembl/ensembl-compara,kumarsaurabh20/ensembl-compara,etapanari/ensembl-compara,ckongEbi/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara,Ensembl/ensembl-compara