[m-rev.] for review: break up simplify.m

[Julien Fischer]

Hi Zoltan,

On Wed, 23 Jul 2014, Zoltan Somogyi wrote:

> This is a cleanup of simplify.m before work on fixing bug 311.
>
> For review by anyone. One point for the reviewer to consider: should we make format_call.m
> a part of the new simplify package? It does its task as part of simplification, but
> the fact that format_call has something to work on is noticed by determinism analysis.

In relation to the format_call module I suggest separating out the
predicate is_format_call/3 and putting it in one of the common utility
modules, hlds_code_util for example.  It should then be possible to make
format_call a private submodule of the simplify package, since
determinism analysis only makes uses of is_format_call/3.

The rest of the diff looks fine.

Cheers,
Julien.