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.