Nitpicks

- RenderStates.Default is used in a way that fits @property better, and it's a backwards compatible change.
- There is no need for RenderTarget.getDefaultView() to return a `const(View)` as opposed to a regular `View`. While const is from the original API, because `View` is a class and not a struct (plus D treats const differently than C++), it ends up more as a hassle. `getDefaultView()` exists to get an easy *mutable* `View` object that fits the window's perspective so that it can be easily changed and set back to the `RenderTarget`. To have it be const means it needs to be casted or duplicated, the latter being a waste (especially since all the function does is create a new view), and both being annoying.