Change AssociationDefinition API wording (#67).

BREAKING CHANGES

6 methods in AssociationDefinition/AssociationDefinitionModel are renamed:
    - getWholeTypeUri() -> getParentTypeUri()
    - getPartTypeUri()  -> getChildTypeUri()
    - getWholeCardinalityUri() -> getParentCardinalityUri()
    - getPartCardinalityUri()  -> getChildCardinalityUri()
    - setWholeCardinalityUri() -> setParentCardinalityUri()
    - setPartCardinalityUri()  -> setChildCardinalityUri()

To adapt your plugins do a search/replace.

See ticket 67.