Now, when creating a remote object in renderer, the browser will
reference the corresponding object by storing it in a strong map. And
when the remote object in renderer is GCed, the corresponding object
will be dereferenced in browser.
When a render view is closed, it's not guarrenteed that all objects'
weak callback would be called. So we must clean up all objects manually
after the render view gets closed.
Basic usage is:
remote = require 'remote'
Window = remote.require 'window'
w = new Window { width: 800, height: 600 }
Still need to do:
* Beter support for Array type.
* Remote objects should cheat devtools.
* Support cross-process callbacks.
