Adjust & pngout d-logo-sketch.png

d-logo-sketch.png and d-logo-sketch-small.png were previously out of
alignment, causing the stylized D to shift left when the two logos
changed. This has been fixed in paint.net, and the edited png has been
compressed with pngout.
Merge pull request #2691 from fysics/master

Adjust & pngout d-logo-sketch.png