Support for tidy layout

[brj1]

I came across this tree layout called the "tidy" layout (1, 2) which is a rectangular format that arranges the branches to minimize the vertical displacement. I thought that I would code it up for ggtree. I followed the algorithm in 2.

I don't think it is amazing, but some people might find it useful.

set.seed(0)
tree <- rtree(50)
ggtree(tree)

ggtree(tree, layout = 'tidy')

[GuangchuangYu]

Maybe misleading:

[brj1]

Again, I don't find this layout amazing. I've added a parameter to give the tips some extra padding so that so that the branches don't get squished together too much.

My above example now gives: