For discussion - removing Now from event raising syntax

## Do not merge this

For #30.

@philippdolder, I had intended to 

1. try to understand how event-raising works now
2. see how to close the gap in your approach

I never got to point 2.

Instead, I just

1. added an implicit converter from `Raise<TEventArgs>` to  `EventHandler` and to `EventHandler<TEventArgs>`, and 
2. made `FakeManager.EventRule.EventCall.IsEventRaiser` pay attention to the new `NowNonGeneric` method that I needed for the `EventHandler` conversion

It's not particularly elegant, but it does allow us to preserver the arguments passed to the raiser, since we're never actually calling `Now` (or `NowGeneric`), so we have access to the original `Raise<TEvents>` object when we need to fire the event.

Anyhow, I thought you might enjoy looking at it.