[rules-dev] Rule Flow

[Mark Proctor]

There is a working Rule Flow implementation in drools-core now (not in 
drools-compiler and the the drl language yet). It works in a similar 
manner to activation groups. Each rule can be a in a RuleFlowGroup when 
that rule activates instead of being added to the Agenda it is instead 
added to the RuleFlowGroup it sits there till it is either de-activated 
or the RuleFlowGroup itself is activated. When the RuleFlowGroup is 
activated it adds all activations to their respective AgendaGroups, when 
all those rules are fired the RuleFlowGroup activates all child 
RuleFlowGroups. See the unit test AgendaTest for how it works.

So currently it does branching but joins still need to be done and 
possibly allowing multiple flows for the same ruleflow network.

I have removed MVEL from core, so MVEL related tests ('from') aren't 
working at the moment. As soon as the jdk1.4 version is working with 
MVEL I'll fix that up.

Mark