Special character pane redesign
Based on the search/replace pane new design, here is the special characters new pane.
smallest change: the characters should be shown with the same font as the content, and, if the character was missing in that font, it should be turned red. it's doable using the get computer style: http://jsfiddle.net/4mxzE/
We'll obviously need to define behavior for the smallest screen (list of unicode range should be inline then).
