Move window out of Host but give host a windows container

[BrentFarris]

There is currently a window inside of Host. We'll rather want a container of windows inside of the host and let the container manage all the various windows and their polling.

[BrentFarris]

I'm thinking that the host can still have a window, but it should be a pointer and passed in. This means the host should be able to operate without a window and creating a host shouldn't also create a window.