atSign has no unicode variant

Prior to this change, atSign was defined as follows:

atSign unicode = text (if unicode then "@" else "@")

Yes, this is the same symbol '\64' and not your font playing tricks on you. Now we define:

atSign = char '@'

Both the LaTeX and the Xhtml backend are updated accordingly.

Merged in https://github.com/haskell/haddock/pull/1544

closed