Merge branch 'model_checker' into alessandro_branch

build.txt

src/main/java/avatartranslator/AvatarActionAssignment.java

src/main/java/avatartranslator/AvatarActionOnSignal.java

...ranslator/modelchecker/SpecificationReachabilityType.java

src/main/java/ui/util/DefaultText.java

src/main/java/ui/window/JDialogAvatarModelChecker.java

ttool/src/test/resources/cli/input/CoffeeMachine_Avatar.xml