Copy editing and formatting improvements.
Inexpensive/generic checks first.
Sharing check is mostly for information-gathering right now.

It might not be a way to filter out windows in the future, but for now
it's the most flexible option.
Always be deleting/refactoring code.
Mouse moved events stop working when you close the first window in the list using ⌥W.
Oh yeah, by the way: ⌥W can be used to close windows.
Animate active status of thumanails.
BailUnless incurs DebugBreak, so switch their use in NNWindowFiltering.
Support for indexed subscripting in the HUD collection view
Share the Switch scheme and disable autoscheming.
Build 64-bit only
Getting Started section
Dispatch NNApplication background tasks to a background queue instead of a default queue.
Dispatch NNWindow background tasks to a background queue instead of a default queue.
No need for a locking queue for single-recursion execution.

First iteration should be normal priority, subsequent iterations can be
background priority.
Return a valid array object even if _windows is empty.

Thanks to @mattt for this trick.
Dispatch subsequent recursions of NNWindowWorker's worker loop to a background queue.
More feedback with animations.
Minor copy editing.
Fire a breakpoint if CGEventTapCreate fails, because we're probably not root.

Issue tracked by #7.