0644 Logical delete flag required for reference data

We would like a logical delete flag on all reference data instances. This is assuming that once a reference instance has been instantiated, it will never be deleted, even if it becomes obsolete in future versions of Epicentre. A boolean, with "true" for a value that is currently valid and "false" for those that are obsolete would do it.

Add status and version information to standard instances

The optional attributes status and version have been added to reference_behavior. Status is a list of standard values controled by an enumerated data type, and version is a relationship to an open reference entity. The status attribute gives information of the status of the instance, for example

Added objects:
ref_epicentre_version (Entity)
reference_behavior.status (Attribute)
reference_behavior.version (Attribute)
ndt_instance_status (Named data type)

make ref_code_alias a subtype of reference_behavior

Ref_code_alias has been made a subtype of reference_behavior so that it can inherit the status and version attributes and is no longer an anomaly.

Modified objects:
ref_code_alias (Entity)
HL1:_High_Level_Model (Diagram)

remove source from ref_code_alias

The direct attribute of ref_code_alias, source, has been removed, because this is now inherited from reference_behavior.

Deleted objects:
ref_code_alias.source (Attribute)
ref_source.code_alias (Attribute)