Tsinfer figure is without "root breaking"

[hyanwong]

I just realised that the tsinfer figure shows the "old" tsinfer behaviour, in which the ultimate ancestor is not broken into pieces. Breaking the root up like this is now the default. So should we show it? The plot would then look something like this:

To compare, this is what it looks like at the moment:

[hyanwong]

The colour scheme doesn't quite highlight the local roots in KwARG (A) and ARGweaver (B), because local roots are inferred to have ancestors that connect them to the grand MRCA.

[jeromekelleher]

Let's go with recent version, after discussion

[hyanwong]

Fixed in #398