Escaped HTML in readme

Escaped the HTML in the readme file so it (hopefully)doesn't have to be
spaced out any more.
Separated interface from backend

The IView and IViewEngine components were moved into a separate project
from the templating engine backend to make it easier to satisfy opposing
goals:

- Expose a minimal API to code that includes the view engine to avoid
cluttering their namespace
- Allow a test harness to acquire full access to the backend for better
test coverage

The division allows normal consumers to reference just the view engine
while testing consumers can additionally reference the backend directly.