Remove make_dlxwrapper from the sage namespace

[slabbe]

make_dlxwrapper is used for creating a dlx_solver from a pickled list:

 $ sage -grep make_dlxwrapper
sage/combinat/matrices/all.py:from dancing_links import make_dlxwrapper
sage/combinat/matrices/dancing_links.pyx:            sage: x = make_dlxwrapper(dumps(rows))
sage/combinat/matrices/dancing_links.pyx:            sage: print make_dlxwrapper(dumps(rows)).__str__()
sage/combinat/matrices/dancing_links.pyx:            sage: x = make_dlxwrapper(dumps(rows))
sage/combinat/matrices/dancing_links.pyx:        return sage.combinat.matrices.dancing_links.make_dlxwrapper, (dumps(self.rows),)
sage/combinat/matrices/dancing_links.pyx:def make_dlxwrapper(s):
sage/combinat/matrices/dancing_links.pyx:        sage: x = make_dlxwrapper(dumps(rows))

This is a follow-up for #11814.

[slabbe]

Since the segmentation fault is now fixed in #11814, I am changing the goal of this ticket (still as a follow-up for #11814).

[slabbe]

I suggest to not use deprecation for this unpickle function.

---

New commits:

​8ee8dd8	Trac #11814: Catch the segmentation fault in dancing links
​25741df	Trac #11814: Merge with 6.8.rc1
​35f074c	Trac #11814: Added not tested flag for segmentation fault
​5495759	Trac #11814: Fix segmentation Fault raised by an assert
​392b62c	Simplify dancing links code
​3a3dd8b	Removed cimport Integer from dancing links
​56c74ed	Better __repr__ for dancing links, added rows method
​e2b82a4	Fix doctest in games/quantumino.py
​1197483	18950: Remove make_dlxwrapper from sage namespace

[slabbe]

Sorry for the long commit list from #11814: only commit ​1197483 needs to be reviewed here.

[jdemeyer]

Running doctests now...