[m-dev.] Deprecating stuff in builtin module

[Julien Fischer]

Hi all,

There's a bit of stuff in the standard library's builtin module that I suspect
we no longer need, namely.

1  The inst aliases 'new == free' and 'old == any'.  These were the names that
HAL used and were introduced into Mercury by G12 so people used to HAL could
pretend they were still using it.

2. The modes 'no' and 'oo'.  Again, these were for compatibility with HAL.

3. The modes 'input' and 'output'.

4. The function promise_only_solution/1 and predicate promise_only_solution_io/4.

I propose to delete (1) and (2) immediately and deprecate (3) and (4). 
Any objections?

Julien.