Better plotting for large trees

To improve readability of large trees I've made the following updates:

1. Line widths on trees decrease in size if there are more than 200 tree tips.
2. Genotype transition trees are plotted on their own page.
3. No more black outlines for the continuous phenotype tree
4. The user now has the option to choose between a phylogram (right facing, square tree) and fan tree. Phylogram is the default. The phylogram ignores tree edge length while the fan uses tree edge length.