changes supporting or noticed due to work on nimbleModel

[perrydv]

This has some mostly minor changes arising from work on nimbleModel.

• Error trap whether a user writing their own nClass initialize method has included super$initialize(...), which they need to.
• Fix a bug in return of full interface objects when a user-written initialize takes arguments before the CppObj argument (that latter of which should be captured in ...)
• Fix bug in recent change to generateCpp handler for Assign that accidentally avoided use of flex_() on the LHS.
• Support set_all_values from a list for nList objects with flexibility for whether the input list is compiled or uncompiled and whether each element is compiled or uncompiled.
• Tests for much of the above, although not as exhaustive as could be.

I am entering this PR before running tests, which I will go do next.

[perrydv]

There is a test failure that appears unrelated and was noted in #192 . I will proceed with merging this PR.