Not-obvious ruby scoping

[schneems]

There are several places where ruby code can be run/evaluated:

• Rundoc configure
• ERB
• Website navigation

ERB supports the ability to have different bindings, and I believe website navigate creates different sessions. It's possible to script everything use pre.erb but that's a little clunky.

We could change the binding so that rundoc configure and the default ERB binding is shared. However for navigation to support different navigations, I don't think we can support having multiple bindings. Either way, it's emergent and not entirely intuitive what iteracts and plays well with what and what doesn't.