Style the typed *and* the correct texts.
When the answer is typed, use the INSERT/DELETE/EQUAL results that the diff engine supplied all the time to style the input *and* the correct texts, similar to the way Anki desktop does now.
Clean up the typed and correct texts a bit.
(Emacs removed some trailings spaces.)
Merge pull request #363 from ospalh/feature-three-way-comparison

Style the typed and the correct texts.