OCL25 — OCL 2.3 : Introduce Lambda functions

OCL already has an implicit form of Lambda function in the intuitive declaration of collect(). This should be formalised and made more versatile. It doesn't seem to be possible to formulate a declaration for collect() without a Lambda Function:

Sequence(T1)::collect(T2)(iterator : T1 | body : Lambda T1() : T2) : Sequence(T2)

The mandatory collect body is a parameter-less Lambda function whose context-type is the class template parameter T1 and the return-type is the operation template parameter T2.

For other iterators the declaration can be just OclExpression since the type is not exploited.