UML22 — add the rule of ``natural termination''

I suggest to add the rule of ``natural termination'': An activity terminates when it has a token in each of its output Activity Parameter Nodes. This removes the need for Activity Final Nodes in most cases, and makes UML less error-prone, since it is an error to terminate without a token in each output Activity Parameter Node. It also makes the languages more consistent, since this rule is used for loops.

see above