Wide layout: Classify: Split equally between the subject and questions.

The subject was shown small again. This seems better.
Remove unnecessary imports.
ExampleViewer: Make the image as big as possible.

By removing the (useless) ScrollView and using scaleType=fitStart.
fitStart aligns to the top-left while keeping the aspect ratio,
which effectively aligns to the top when we use
layout:width=match_parent.