Initial ruby19.y import.
Ignore warnings in the shortcut parsing mode.
ruby19.y: Implement (or correct) all parser tests
ruby19.y: Revert rule change
ruby19.y: Proper top_stmts
ruby19.y: Don't pass around nil in opt_by_decl
ruby19.y: Cleanup:

- Indentation fix
- Always use multiline-block
- Remove `result = val[0]`
ruby19.y: 1.8 compat
Merge pull request #2 from judofyr/initial-ruby19

+ ruby19.y: transfer compatible rules from ruby18.y.
Merge branch 'master' into ruby19
Update README.
Add tests for ruby19.y.
ruby19.y: Don't create an (arg) node right in f_norm_arg; defer it.
Merge branch 'ruby19'