Merge pull request #17 from philipnilsson/rank2

Use Rank2 types to simplify type signatures of parsers.
Merge pull request #18 from philipnilsson/es5

ES5 - add missing syntactic productions
removed the unnecessary import -- fixed the build
Changing the syntax to make more sense (since we are breaking compatibility anyway)
Added the Parser API resembling that of the ES3 branch
Modified the PrettyPrinter API to follow that of the ES3 branch + small refactorings
Removed the IfSingleStmt constructor that's not produced by the parser anymore
Added parsing rules for automatic semicolor insertion, rules 1 and 2. Still need to apply rule 3.
Adding some tests in Tasty
Adding tasty to dependencies
Add ecmascript 5 tests to cabal. Upgrade to tasty framework
Undo debug change
More tests
Starting auto-insertion of semicolons
Fix bug, use sepBy1 in commaExpression as according to spec
Fix test for empty for-loop, looks nicer!
Complete auto-semi inseration
Tests for auto-insertion of ;
Reintegrate with achudnov