Fix half/third cycling for quantized-height windows

Some windows like Emacs and Terminal quantize their heights, so they
never satisfy the exact height requirement that triggers cycling from
half to two third to one third.

The original patch by @stevenrobertson didn't check height at all, which
prevented this problem but causes an unexpected jump from states like
top-left-quarter directly to left-two-thirds, when it should stop at
left-half first.

This patch uses the existing `SpectacleWindowCalculationFudgeFactor`
instead. I use double the value for this case, because height is often
quantized to a full line of text, so 8 pixels is not quite enough.
Merge pull request #152 from ef4/height-fudge-factor

Fix half/third cycling for quantized-height windows