Use hide/show on buttons, not displace

Buttons don't properly support calling style with displacement values yet, but
the displacements were only to move things on/off screen, so just hide/show
instead.
Trigger redrawing on game of life

The existing game of life code wasn't properly triggering element redraws when
the style of a cell changed states. This meant that clicking run would go, but
only show you the results when you forced a redraw by other means (i.e.
resizing the window).

This commit adds a redrawing trigger for the common `style` call and updates
the sample to be more cautious about style-setting to avoid masses of updates
all at once.
Restore original game of life, make adjusted copy
Merge pull request #650 from shoes/button_displace_style

Further fixes for samples/expert-game-of-life.rb

Resolves #538