Merge branch 'release/v0.6'

.gitignore

.idea/checkstyle-idea.xml

.idea/codeStyles/codeStyleConfig.xml

.idea/libraries/junit_junit_4_13.xml

.idea/libraries/lib.xml

.idea/misc.xml

Contacts.iml

README.md

idatx2001_checks.xml

lib/derby.jar

lib/derbyclient.jar

lib/eclipselink.jar

lib/hamcrest-core-1.3.jar

lib/jakarta.persistence_2.2.3.jar

lib/junit-4.13.jar

lib/mysql-connector-java-8.0.19.jar

src/no/ntnu/idata2001/contacts/AppVersion.java

...a2001/contacts/controllers/ContactsAppFXMLController.java

...o/ntnu/idata2001/contacts/controllers/MainController.java

src/no/ntnu/idata2001/contacts/model/AddressBook.java