Small sub-diagrams of Umple's internal design

[TimLethbridge]

Currently at https://umple.org/metamodel several huge diagrams of Umple's design can be seen. These are useful (perhaps) and can be hovered over and clicked on to jump to the Javadoc for the respective class.

However, it would be good to create a set of smaller diagrams, e.g. one that focuses on just classes and associations, one that just focuses on the very central core of state machines, one that focuses on generators in general (and specific generators even), one that focuses on parsing, and so on. Probably a dozen small diagrams could help people to be able to explore the Umple architecture better.

These should be set up using filters, the same way the existing three digrams are displayed.