Fix some bugs in the translation from TML to AVATAR Sec

src/main/java/tmltranslator/TMLDecryption.java

src/main/java/tmltranslator/TMLEncryption.java

src/main/java/tmltranslator/toavatar/FullTML2Avatar.java

src/main/java/tmltranslator/toavatarsec/TML2Avatar.java

src/main/java/ui/ActivityDiagram2TMLTranslator.java