* also changed xml elements in sourcegroup settings that specify the used language standard, so that one sourcegroup can maintain multiple language standards
* added migration and migrated sample projects
* fixed error columns are not saved to database correctly
* implemented setting JRE System Library paths in app settings
* added detector for JRE System Library that not use Java Runtime specified in AppSettings but detects JRE on its own by reusing the JavaPathDetector.
* added option to use JRE System Library in JavaSourceGroup
* NameHierarchy now looks like this: <delimiter>\tm<all the rest>
* made new baseclasses for SettingsMigration and SettingsMigrator
* Use the migration system for SqliteBookmarkStorage as well