Fix ceylon/ceylon.language#466 by intercepting evaluation of message on Throwable instances. Also fithe similar thing we do intercepting suppressed on Throwable, since what we had before didn't handle static references.
Add test for ceylon/ceylon.language#466
Add test for the interception of evaluation of suppressed on Throwable instances.
Fix up existing tests now we intercept Throwable.message and Throwable.suppressed.