Complete refactor

- Extracted much functionality into Base and greatly simplified code
- Simplified DSL
- Blocks yield if an argument is given, instance-eval if not
- HTML rendering extracted into View class
- Model is now a "simple" data structure without rendering code mixed in
- Hierarchy is now Dashboard 1->* Pages 1->* ( TabSets 1->* Tabs 1->* ) Sections -> 1->* Widgets
- Other stuff.  Look at the code.