NetNewsWire for Mac 7.3b4

• Made small thumbnails fill the space (aspect fill) — images are cropped from the sides and bottom, never the top, so faces and other important parts are more likely to stay in view
• Gave large thumbnails rounded corners, to match small thumbnails and feed icons
• Removed the background color behind thumbnails, and added a faint placeholder color that shows until a thumbnail loads
• Fixed footnote popover positioning near the edge of the article view and after resizing the window on Duo
• Fixed bug where the last article in the timeline had a separator below it (when separators are turned on via the hidden preference)