Inconsistent use of type/types and datatype

Created by: daniwelter

There are 6 instances of types in the model, 4 of type and 1 of dataType. Most of these reference the annotation schema, except for Dataset.types and Dimension.datatypes, which reference the dataType schema. The type/types use should be reviewed to ensure that the pluralisation is always appropriate. If possible, Dataset.types should be changed to reference annotation rather than datatype.