diagrams/diagrams-lib — pull request #184 by jeffreyrosenbluth (2014-05-05 00:36:22+00:00)
Title: arrow head size specify in terms of width instead of radius

I think it's more natural to specify the width of the arrow head and tail,
as opposed to the radius of the circle the circumscribes the head / tail.
This also lets us reinstate our `widths` traversal which is very useful,
especially for things like the uarrow isssue.