CompilerTest: Clear the class loader cache even when the thing we're executing throws an exception (required for #1173).
Issue #1173: test: Add some tests for new, better recovery
Issue #1173: test: We should have two errors about dynamic
Issue #1173: Add a visitor for adding errors to nodes which we don't support in some way
Issue #1173: Change error handling so that we only abort transforming a
declaration if there are errors in the Ceylon declaration itself (excluding
any errors in the body or specifier). When a statement (including its
child expressions) contains an error replace it with a throw.
Issue #1173: Generate a .class file even if a class has errors.