* (aadlba.ecore,
   org/osate/ba/aadlba/*.java,
   org/osate/ba/aadlba/impl/*.java):
   - support PropertyReference. UML Diagrams will be updated later.
   - delete useless classes (BehaviorProperty; BehaviorPropertyValue; BehaviorEnumerationLiteral).
   - create class FeatureHolder, super type of:
     - PortHolder
     - ParameterHolder
     - SubprogramAccessHolder
     - DataAccessHolder
   - create class SubcomponentHolder, super type of:
     - DataSubcomponentHolder
     - SubprogramSubcomponentHolder, also created
   - PrototypeHolder is no longer the super type of GroupPrototypeHolder
   - DataSubcomponentHolder is no longer a GroupableElement
* (AadlBa.g,
   org.osate.ba/src/org/osate/ba/parser/*.java):
   - support property reference syntax
   - fix ambiguity between value variable and properties: delete fact_value ANTLR rule.
   - raise ambiguity between property reference and property constant
   - delete behavior enumeration literal ANTLR rule
   - update syntax comments
* (declarative.ecore,
   org.osate.ba/src/org/osate/ba/declarative/*.java,
   org.osate.ba/src/org/osate/ba/declarative/impl/*.java):
   - add declarative classes to support property reference.