EWCE should use One2One instead of data("mouse_to_human_homologs)

[bschilder]

Replaced One2One and mouse_to_human_homologs with orthogene in most functions.

Progress

• [x] drop_uninformative_genes.
• [x] generate_celltype_data.
• [x] standardise_ctd
• [x] filter_genes_without_1to1_homolog
• [ ] fix_bad_hgnc_symbols
• [ ] fix_bad_mgi_symbols
• [x] prepare_genesize_control_network

Will add more to this list as I find them.