XD-2107&1048

I saw some weird behavior whereby metrics named `foo` and `'foo'` get created, but for the purpose of centralizing demo content, I'm issuing the PR.

PS: we should definitely have automatic creation of option `fooExpression` when option `foo` exists
Previously alpha was set at counter creation time (at handler initialization time). But now, the counter name is not known until a message arrives. So the handler has to store it. Everything else is a consequence of that