Auto merge of #2071 - aarzee:master, r=alexcrichton

Whitespace: remove leading newlines; replace lines containing only whitespace with empty lines; replace multiple trailing newlines with a single newline; remove trailing whitespace in lines.

Images: Compress PNG files with zopflipng, JPG files with mozjpeg jpegtran, and GIF files with gifsicle.

This PR was created semiautomatically.