Adds several general fixes and minor improvements

Changes getisCaseOf in IConceptDescription to return Set<IReference> instead of Set<String>
Renames getisCaseOf in IConceptDescription to getIsCaseOf
Renames IDataSpecificationIEC61630 to IDataSpecificationIEC61360
Changes types from String to LangStrings in IDataSpecificationIEC61360
Changes getParent and getAssetIdentificationModel in AssetFacade to use facades
Changes getParent in ReferableFacade to use facades
Changes setConceptDescription in ConceptDictionaryFacade to use Reference instead of String
Adds IQualifiable to ISubModel
Adds getModelType to ISubmodelElement
Changes return type of getQualifierValue in IQualifier from Object to String
Changes types of getValue and setValue in ISubmodelElementCollection from Object to ISubmodelElement
Adds null check to getQualifier in QualifiableFacade
Adds null check to getKeys in ReferenceFacade
Changes getQualifier and setQualifier in SubmodelFacade to use IConstraint instead of String
Changes ctor of Formula to use IReference instead of Reference
Fixes ctor of Qualifier
Adds createAsFacade function to all SubmodelElement types
Changes buildXmlMap in XmlParser to ignore comments in XML
Deletes duplicate IReferenceElement

Change-Id: I632d37fe1f3ef749f7d1ff3b6ee3fd61205c5448
Signed-off-by: Maximilian Conradi <maximilian.conradi@iese.fraunhofer.de>
42 files changed