Update `LANGUAGE` pragma lists

`CPP` was missing from many `LANGUAGE` declarations, and a few
extensions become redundant with Haskell2010.

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Update `hoopl.cabal` to `cabal-version>=1.10`

...also renames `CHANGES` to `changelog` so Hackage can display it, and
adds an entry for 3.9.0.0

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>
Add Travis-CI `.travis.yml` script

Signed-off-by: Herbert Valerio Riedel <hvr@gnu.org>