RazorTextWriter represents the result of rendering a page as a sequence of
strings rather than a concatenated string. This avoids building up large
strings in memory.
* Introducing RazorPage and RazorPageOfT that represent the Razor
execution aspect of view execution. Moving view execution hierarchy behavior
(Layout, partial views etc) into a separate RazorView type.
* Renaming IVirtualPathViewFactory to IRazorPageFactory,
IRazorViewActivator to IRazorPageActivator
* Renaming VirtualPathViewFactor to FileBasedPageFactory to
correctly reflect what it does.
Fixes#814
Pranav K