Added non-computation state of property when not already computed

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

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

...artranslator/modelchecker/SpecificationPropertyPhase.java

...tartranslator/modelchecker/SpecificationReachability.java

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