QVT11 — add the following operations to mutable lists

In the spirit of issue #13228, and in conversation with Mariano Belaunde, we think it is worth considering also adding the following operations to mutable lists. As specific usages of 'removeAt()': 'removeFirst()' and 'removeLast()'. And also: 'removeAll(Collection(T))'. Notice that this one includes the case of removing values specified inside mutable lists as long as ListType inherits CollectionType. Suggestion: Add the following text to section 8.3.8: - List(T)::removeFirst() : T Removes the first value of the mutable list. The return value is the value removed. - List(T)::removeLast() : T Removes the last value of the mutable list. The return value is the value removed. - List(T)::removeAll(Collection(T)) : Void Removes from the mutable list all the values that are also present in the specified collection.

And remove() from Issue 13228. A List is not a Collection so we need two removeAll's.
Additional operations in Issue 19146.
Disposition: See issue 19146 for disposition