Add option to toggle display of angle quotes in the Diff Viewer

It would be helpful to be able to toggle the display of these indicators. The "Ignore Whitespace" option does not affect them, but I'd prefer a separate option anyway. I do care about whitespace changes, and having these marks in the "After" pane can make it difficult to tell if a change fixed or created an alignment issue. Here's a screen capture of one in the "Before" pane.