Changed structure of GetDataForCache, doesn't work yet
* Adapted GetContentTypes() to return AttributeDefinitions of Shared AttributeSets
* Minor Performance Optimization for GetEntityModel()
* Finished GetDataForCache() to build correct EntityModels
* Adated AttributeModel and TypedValue to return null if no value is specified when using Language Indexer
* Adapted EntityJavaScriptModel to handle empty EntityRelationshipModel
* Adapted Field Templates to use GetMetaDataValue<>()
Minor Fixes
Fixed EntityModel.Title Reference
Minor Fixes. Extended Testing Page.
Adapted how EntityModel (IEntity) is generated. Uses now ContentType Definition instead of actual values. So IEntity has now all Attributes always, even when there's no value stored.