[Nickle]raise of undeclared exception is ignored

[Carl Worth]

Here's another quirk:

	> raise Foo(bar);
	> #huh? no complaint about bar? no exception raised?
	>
	> exception Foo(int);
	> raise Foo(bar);
	->     raise Foo (bar);
	No symbol "bar" in namespace
	> # that's better
	>
	> int bar = 0;
	> raise Foo(bar);
	Unhandled exception "Foo"
        0
	>

-Carl

PS. Someday soon I promise to actually dig into nickle internals so I
could actually contribute by fixing bugs rather than just reporting
them. :)