[m-rev.] for review: move towards packing args with secondary tags

[Julien Fischer]

On Wed, 6 Jun 2018, Zoltan Somogyi wrote:

> For review by anyone, but I would like Julien to have a look at
> the diff to uint*.m, because I don't know the right casts for C# and Java.
> This could happen post commit, since having an incomplete implementation
> of a new predicate in some unannounced modules for a day or two
> should not pose any problems.

I think you're missing some casts in some cases; go ahead and commit
this and I'll fix the C#, Java implementations this afternoon.

Julien.