Restore Default status of OK button in command bar

Rather than use the actual .Default property (which causes a myriad of
unpleasant interactions across dialogs), we now simply set the focus to
the OK button manually, at initialization time.
Profile and improve perlin noise class

Besides fixing some previously unknown bugs with Steve M's code, this
update includes a number of performance improvements for the Perlin
Noise engine.  As we will be leaning on it more heavily for noise in the
future, this was a good time to get these changes merged.

Similarly, some improvements and updates to the Figured Glass tool
(which uses perlin noise heavily, and thus makes for a good testing
ground) are included.