dot-deno: internal function
In Chien-Hsun/rePhylo: Re-investigating and Improving Phylogenies

Internal function of rePhylo

1	.deno(xx, ref, testtree, testtips, c.out, split, sub_coverage, max.tip, bp)

`xx`	one of allnodes
`ref`	ref
`testtree`	testtree
`testtips`	testtips
`c.out`	logical. Whether the closest outgroup species are required to exist. Defaults to `FALSE`.
`split`	a character indicates the symbol used to separate species names and gene id for gene family trees. Defaults to `NULL`.
`sub_coverage`	a numeric to specify the species coverage of the clades of each node. Used as percent when <= 1, and as count when > 1. Defaults to `NULL`.
`max.tip`	an integer specifying the max number of tips for the coverage filtering. Applied only when sub_coverage is set as percent (<= 1). Used as a cutoff for coverage as N tips as for deep nodes having large clades. Defaults to `NULL`.
`bp`	a numeric specify the minimum bp value for the node. Defaults to `NULL`.