Feature: Separate View Instantiation from ExecutionContext Targeting

[EisenbergEffect]

At present, to create a view, you must supply an execution context. Afterwards, this context is permanently tied to the view. We should separate these two things so that we can re-use view instances by re-targeting them to a different execution context. There are two primary use cases off the top of my head:

1. The router can use this to optimize rendering of frequently accessed routes. This can be done by implementing the router's corresponding directive to cache views internally and re-target them to different controller instances. In fact, any template directive could use this technique (even allowing caching behavior to be configured by the developer).
2. Performant, infinitely scrolling lists will want to create a number of view instance up front and re-use those instances by simply re-targeting each template item to different data and using some css3 transforms.