make Preview more intelligent

[mikekazakov]

• ability to move focus there
• add option to show it in a floating window
• support selection in PDFs
• show directory size, file owners, permissions and stuff

[mikekazakov]

Preview should show more information for an app, such as basic file attributes but also useful ones like version information, UTIs, binary type. Similarly the preview for folders should show the number of subfiles at the first level, perhaps even a list of them.