Changelog for pretty-show-1.6.9

Changes in * Correct license in srouce files. Changes in * Correct the 'License' field in the Cabal file to match the license (MIT) Changes in 1.6.8: * Move source-repository pragma to top-level. Changes in 1.6.5: * Rename CHANGES to CHANGELOG to work with hackage. Changes in 1.6.4: * Drop dependency on happy >= 1.19 Changes in 1.6.3: * Add Safe Haskell annotations * Add CHANGES file * Add generated parser to package again. We do this, because otherwise the package fails to build on systems that do not have `happy`. This is a bit questionable, but hopefully it won't be too much of a problem.