[m-rev.] for review: support optional package version information

[Julien Fischer]

On Sat, 9 Sep 2023, Zoltan Somogyi wrote:

> On 2023-09-09 00:43 +10:00 AEST, "Julien Fischer" <jfischer at opturion.com> wrote:
>> library/library.m:
>>     Add version/3, which returns the package version string in addition
>>     to the version and fullarch strings.
>
> I have a slight preference for separate predicates (or functions)
> returning the Mercury version, the package version, and the fullarch,
> but I can see that there is no point in switching to that now.
> However, I think it would be better to add any NEW info, such as the
> package version, as something you can get on its own.

Ok, I've removed version/3 and added the function package_version/0.
I suggest we add the following functions as well:

   :- func mercury_version = string. % Returning MR_VERSION
   :- func architecture  = string.   % Return MR_FULLARCH

(We can deprecated version/2 eventually.)

Julien.