Manually display nodes

Method to force display of nodes (main-thread affined). Added a sample project that will demonstrate how to manually display nodes. Removed the UIWindow layer pool hack.
this isn't quite right, grab me offline to discuss =]

the key idea behind ASRangeController is that if a node is in the working range, it's attempting to display itself; if it's not in the working range, its layer contents are culled to save memory.  adding a node to the previous hacky "working view" is equivalent to calling this new `-display` method on it; when we remove it from the working view, we call `-reclaimMemory` on it, meaning that a new `-display` is required for it to appear again.

so, if we call `-display` here, we have two problems:  (1) sizing becomes a drastically more expensive operation, with unbounded memory usage because culling doesn't apply, and (2) once a node's been culled, it won't re-render until it actually comes onscreen.  you can verify this with delayed display — nodes will no longer be rendered in advance and will remain blank until *after* you scroll.