HUGE ITTSW Checkin. For those only interested in the short version, it is as

HUGE ITTSW Checkin.  For those only interested in the short version, it is as
follows:  ITTransientStatusWindow is now feature complete except for positioning. All
currently planned effects work, and you can use the Showcase to play with them.

- Renamed the visibility state constants, removing the string "StatusWindow" from
them, since window visibility is a protocol not limited to ITTSW.

- Implemented ITSlideHorizontallyWindowEffect and ITSlideVerticallyWindowEffect.
This completes the 1.0 planned suite.

- Implemented a heuristic for effects to be able to release themselves when idle,
so that an effect can finish a transition smoothly, and release gracefully,
instead of crashing.

- Made all effects return the window to normal after vanish, so that they don't
have to worry about doing so when they appear.  Some do anyway.

- Implemented timed exit, and the various logic to make the two exit modes work
seamlessly.

- Modified the Showcase Controller and nib to allow use and testing of all ITTSW's
features.  Unavailable features are disabled.  Removed the switch/case block and
used an if/else block instead.  Switch/case sucks.  Hard.

- Decided against a separate cancelVanishEffect.  I like our way better, and I
think it's a better UE than Apple's, so... fuck Apple.  Fuck them in their stupid
asses.

REMAINING:
----------

- Positioning
- MT Status Window Controller.

Should be able to complete at least one of those tomorrow.  Positioning comes first.