SAHA2Seurat matching convention

[domjacri]

need to fix so that it uses cluster/best_match or old_names/new_names

[richardmustaklem]

Fixed. Please close when tested. Also moved some new additions on main vignette for customization. Important note - this function will rewrite your seurat object's active Idents and assumes your active idents was the same from start to finish. This is used for Dimplot() function.