Issue #1522: Erasure rules for Error and Throwable.
Issue #1522: Model loader changes for Throwable/Error
Issue #1522: Because we erase c.l.Error to j.l.Error, which doesn't implement ReifiedType, we need a parameter to determine whether $ should be @Override or not when subclassing c.l.Error.
Issue #1522: Minor change to how we transform 'throw'.
Issue #1522: test: Change existing tests now that we have Throwable/Error
Issue #1522: test: Add new test for declaring an using Errors and Exceptions
Issue #1522: test: Extend the IsOperatorTest to cover exception types
Issue #1522: Stop erasing c.l.Exception to j.l.Throwable, and fix up resources and try/catch.
Issue #1522: test: fixup to the ExceptionTypes test
Issue #1522: test: Changes now that Resource is in terms of Throwable not Exception
Issue #1522: test: Fixup now we erase c.l.Exception to j.l.Exception (not j.l.Throwable).