CLP(ℤ) ante portas

[triska]

Scryer Prolog is now very close to supporting CLP(ℤ)!

The remaining issues that need to be resolved before I can create a pull request are:

1. Goal expansion must work for (\+)/1 (CLP(ℤ): Unexpected existence error #249).
2. The most worrying is CLP(ℤ): Query fails unexpectedly #255. I need to find out why this fails, and it is hard to tell how complex this is and how long it will take. I am working on it. [resolved]
3. To debug (2), I need a reliable toplevel that correctly tells us all residual goals. This is Toplevel should use copy_term/3 to show residual goals #254. [resolved]
4. Algorithms devised by Prof. Jean-Charles Régin have been a huge motivation for my work in the area of constraints, and I would like to spell his name correctly in the CLP(ℤ) source code. This is non_prolog_character #219. [resolved]
5. Support for the discontiguous directive would be useful (Discontiguous predicate definitions would be useful for CLP(ℤ) #229) to keep logically connected definitions together in the source file.

Mark, thank you for all the work you have already put in to get this close! Please focus on the more urgent things (such as #95 and other discussed issues), and I am looking forward to filing a pull request that provides CLP(ℤ) for Scryer Prolog as soon as everything above works!

[triska]

Thank you for resolving almost all these issues.

I have filed #312 to finally make CLP(ℤ) available in Scryer Prolog, and I am closing this issue.

Congratulations Mark, well done!