Fix ghc-parser on GHC 7.8.3

In GHC 7.8.3, GHC's parser changed a bit, causing ghc-parser to fail to
build.  I fixed it by following the instructions on issue #268.
Merge pull request #270 from kini/ghc-7.8.3-fix

Fix ghc-parser on GHC 7.8.3
Bump bounds
Update hlint usage
Merge pull request #274 from bgamari/master

Various updates
Adding version requirement for HTTP
Version bump to 0.4.2.0
Update readme. Closes #265
Move code cell config earlier, closes #257
upgrade virtualenv to 1.11.6
refactor build script to allow both all and display
make Diagrams notebook compatible with recent Diagrams versions