Linktocontent icons in 16x16 pixels

Issue Summary

I've been wondering why icons Linktonode and Linktomenu in the editor always looked so blurred as if the whole button was disabled.

I found out that it was because the icons are 20x20 pixels in dimensions. The editor scales them down to 16 and thus blurrs the edges. As I use Linktocontent, I've reconstructed the icons to fit the expected size, see the attachment.