Merge branch 'alessandro_branch' into 'master'

doc/avatarmodelchecker/images/modelcheckerwindow.png

doc/avatarmodelchecker/ttool_avatarmodelchecker.tex

src/main/java/avatartranslator/AvatarExpressionSolver.java

src/main/java/avatartranslator/AvatarSpecification.java

src/main/java/avatartranslator/AvatarStateMachine.java

...ava/avatartranslator/modelchecker/AvatarModelChecker.java

...tartranslator/modelchecker/CounterexampleQueryReport.java

...va/avatartranslator/modelchecker/CounterexampleTrace.java

...in/java/avatartranslator/modelchecker/SafetyProperty.java

...vatartranslator/modelchecker/SpecificationActionLoop.java

...ava/avatartranslator/modelchecker/SpecificationState.java

...anslator/modelcheckervalidator/ModelCheckerValidator.java

src/main/java/cli/Action.java

src/main/java/ui/AvatarDesignPanelTranslator.java

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

src/main/java/ui/window/JDialogUPPAALValidation.java

.../src/test/java/avatartranslator/AvatarExpressionTest.java