+ latest updates to the meta-model implementation (breaking changes, other components still to be aligned)

* changed actualParameter to argument in TDReference and ActionReference
+ added conformsTo(name) operation
* changed SimpleDataType extension to [0..1] and adapted operations
+ added resolveDataType to PredefinedFunctionCall, DataElementUse
* renamed operation extending to isExtending
* changed Constraint.quantifier to DataUse
+ updated GenModel

+ fixed #13 and #14
+ added resolveDataType for LiteralValueUse
+ added unassignedMember to CollectionDataInstance
+ changed super-class of Assignment to AtomicBehaviour (and added getParticipatingComponents implementation)
+ added DataUse.isEffectivelyStatic operation
+ changed StructuredDataType.extension to 0..* (multiple extensions)
+ changed SimpleDataType.extension to 0..* (multiple extensions)

+ extension for simple data types
+ data element use proposal