Parameter templates of Observable methods accepting Supplier have been improved to allow more strictly typed client code

It is possible to write
```java
	reactor.notify("test", new Supplier<Event<String>>() {
		public Event<String> get() {
			return Event.wrap("Hello, world!!");
		}
	});
```
instead of 
```java
	reactor.notify("test", new Supplier<Event<?>>() {
		public Event<?> get() {
			return Event.wrap("Hello, world!!");
		}
	});
```
now.