Renamed list functions returning a plain array to toArray()
Fixed Fingerprint.getDescription()
Added SiteLinkList.getSiteIds()
Added Term.setLanguageCode()
Added setters to TermGroup
Updated wikibase.datamodel ResourceLoader module dependencies
Implemented StatementGroup
Implemented StatementGroupList
Implemented ClaimGroup
Implemented ClaimGroupList
Consolidated equals() functions
Use StatementGroupList in Item
Use StatementGroupList in Property
Coding style improvements
Implemented OrderedList

Apart from slimming down the code considerably offering a generic list interface,
this removes rather useless uniqueness constraints from ClaimList and SnakList.
Implemented UnorderedList
Added Group
Renamed OrdererList to List and UnorderedList to Set
Implemented Groupable
Removed obsolete tests