Update bug summary
Change method->function
Default values for ref args should not be allowed, so turn this into
an "error message" future.
Slight change in bug summary to be more specific.
Add a future for default values for const ref arguments to functions.
Merge pull request #343 from sungeunchoi/test

Update a few futures

- Update text of test/functions/lydia/syntax-error-unclear-message*.future [reviewed by @lydia-duncan]
- Change test/functions/tzakian/implicit_arg_pass_by_ref.future  into an error message future
- Add test/functions/sungeun/const_ref_arg_default_value.future for default values for const ref arguments