[WIP] Allow Fact(s) to be grouped and routed by multiple criteria

[Wedjaa]

The concept is quite simple: a Fact may have multiple Keys and can transform - enrich - a Fact based on the Key that's being used.

The Fact class has two changes:

1. extractKey was changed to extractKeys: this method, rather than returning a single Key will return a Set of one or more keys. It's up to the implementation of the Fact to decide what Key(s) it should return. In the Gameplay example: extractKeys will return two Key(s) - one for Player grouping, that uses the playerId as grouping key, and one for Game grouping, that uses the gameName as grouping key;
2. a new method forKey was added to the Fact class: the Fact classes implementing this method will decide how to enrich the instance of a Fact depending on the Key value and return the enriched instance. In the Gameplay example: the fact will have a factGroup set to the Key criteria [see below]. This allows the rules to filter duplicate Facts coming their way.

The Key class has one main change: it has a new property - called criteria - that is a label for a specific Key implementation. This change allows the forKey method of the Fact to have some more information about a Key to make an informed decision on what to do about it.

Lastly the Putter class was changed to take advantage of these changes: when a Fact is received it will insert in the Cache one instance of the Fact for every Key returned by extractKeys, transformed by the forKey method.

This is a WIP.

[fmarinelli]

Thanks for your PR, I saw there's a lot of changes compared to master branch.

Are you available sometimes in the future to talk about it?

[Wedjaa]

I could try and get you on Skype. When are you available.

[ugol]

We are both available now on IRC, channel #drools