Lowercase the "apply WebVTT cue settings" definition

For consistency with e.g. "collect WebVTT cue timings and settings"
Refactor how and when "apply WebVTT cue settings" is invoked

This factors out the common "Let nodes be" and most importantly makes
the algorithm actually return the CSS boxes.
Merge pull request #82 from foolip/reorganize-rendering

Refactor how and when "apply WebVTT cue settings" is invoked
Remove effect of rtl / ltr on position related rendering for non-snap-to-lines.

It was an oversight to leave this in the rendering section - text position is
supposed to be calculated always from the left edge for horizontal cues or top
edge for vertical cues.
Merge pull request #102 from foolip/rtlPosition

Remove effect of rtl / ltr on position related rendering for non-snap-to-lines.
Improve on some of the wording.
Fix some typos.
Be consistent when referring to "text alignment".
Merge pull request #103 from foolip/positionTypos

A few preparatory changes to position related spec text.
Merge commit '778b966fd85caf39f88085a140f305b00d4c3c36' into revert-position-size-align
Merge commit '28f3cb2a09fffd6bfbfa644d16755043759d7482' into revert-position-size-align

Conflicts:
	webvtt.html