Namespace definition ordering for gcylc dot and tree views.

Addresses #160.

Tree view: affects the default sort order
Dot view: affects namespace list order

![defn-order-suite](https://f.cloud.github.com/assets/2362137/2212840/0e0164be-99b8-11e3-8b41-0aaa029d87b0.png)
![defn-order-gcylc-flat](https://f.cloud.github.com/assets/2362137/2212846/14785b36-99b8-11e3-9d26-cdccc61d003e.png)
![defn-order-gcylc-grouped](https://f.cloud.github.com/assets/2362137/2212848/18fae9bc-99b8-11e3-9e6a-61f8bc679ed5.png)