[HOpenGL] Haddock documentation on Travis CI

[Sven Panne]

2013/8/25 L Corbijn <aspergesoepje at gmail.com>:
> The Travis CI build environment document states that they use "Haskell
> Platform 2012.2.0.0". Assuming that this is provided by the
> haskell-platform package from ubuntu the documentation can be
> installed by invoking
>
> sudo apt-get install haskell-platform-doc

Cool tip! Adding

  - sudo apt-get update -qq
  - sudo apt-get install -qq haskell-platform-doc

at the start of the 'before_install:' sections of the Travis CI
configuration files really seems to do the trick, I opened a ticket
for this issue (https://github.com/travis-ci/travis-ci/issues/1351)
already, but I'll change this into a proposal to have
haskell-platform-doc pre-installed for Haskell projects.

Cheers,
   S.