update link to attribute grammar article
Merge branch 'master' of github.com:simonmar/happy

* 'master' of github.com:simonmar/happy:
  Get rid of warnings in Setup.lhs
  Add vim temp files to .gitignore
  Turn on -Wall (and remove defaulting warning) and cleanup warnings
  Add the usual suspects and more to .gitignore
  Remove tabs and trailing whitespace
  Removed trailing whitespace
  Corrected section "Using Happy with GHCi"
  tests/Makefile: fix precious files
  tests/Makefile: switch to explicit package imports
  cabal: add missing tests from distribution
  doc: make happy.1 be buildabale with doc/configure