add function to decide whether elements are automatically refreshed or not when they are retrieved from database
add a function to switch deep refreshing
add a new db class to represent clone genealogy
override methods in Object
add a class that represents many-to-many relationship between clone genealogy and clone class
remove clone classes from genealogy and use clone class mappings instead
add DAO for CloneGenealogy
[BUG_FIX] collect the query to get revision in a version
[REFACTORING] collect misspelling of a method
add DAO for CloneGenealogy in DBManager