refactored LTL operators and their tests

...re/src/de/prob/core/domainobjects/ltl/CounterExample.java

.../core/domainobjects/ltl/CounterExampleBinaryOperator.java

...rob/core/domainobjects/ltl/CounterExampleConjunction.java

...rob/core/domainobjects/ltl/CounterExampleDisjunction.java

...de/prob/core/domainobjects/ltl/CounterExampleFinally.java

...e/prob/core/domainobjects/ltl/CounterExampleGlobally.java

...de/prob/core/domainobjects/ltl/CounterExampleHistory.java

...rob/core/domainobjects/ltl/CounterExampleImplication.java

...e/prob/core/domainobjects/ltl/CounterExampleNegation.java

...rc/de/prob/core/domainobjects/ltl/CounterExampleNext.java

...rc/de/prob/core/domainobjects/ltl/CounterExampleOnce.java

.../prob/core/domainobjects/ltl/CounterExamplePredicate.java

...rob/core/domainobjects/ltl/CounterExampleProposition.java

...de/prob/core/domainobjects/ltl/CounterExampleRelease.java

...c/de/prob/core/domainobjects/ltl/CounterExampleSince.java

...c/de/prob/core/domainobjects/ltl/CounterExampleState.java

...prob/core/domainobjects/ltl/CounterExampleTransition.java

...de/prob/core/domainobjects/ltl/CounterExampleTrigger.java

...b/core/domainobjects/ltl/CounterExampleUnaryOperator.java

...c/de/prob/core/domainobjects/ltl/CounterExampleUntil.java