provide xgcd for new polynomial rings through _xgcd_univariate_polynomial

[saraedum]

Currently, to add xgcd functionality for a new polynomial ring, one needs to add a specialized subclass of PolynomialElement.

The attached patch allows rings to provide a _xgcd_univariate_polynomial method which will be called by PolynomialElement to compute xgcds.

This is similar to #10635, #13442.

Depends on #13628
Depends on #18461
Depends on #18467

CC: @sagetrac-boerner

Component: basic arithmetic

Keywords: sd59

Author: Julian Rueth

Branch/Commit: 828b5fc

Reviewer: Peter Bruin, Bruno Grenet

Issue created by migration from https://trac.sagemath.org/ticket/13629

[saraedum]

Changed dependencies from #13628 to #13628, #13442

[saraedum]

Changed dependencies from #13628, #13442 to #13628

[saraedum]

Attachment: trac_13629.patch.gz

[saraedum]

comment:4

I want to remove {{self}} from the docstrings.

[nilesjohnson]

Branch: u/niles/ticket/13629

[nilesjohnson]

comment:7

rebased to sage 6.0 and converted to git branch; no other changes

merges cleanly in local repository in spite of what trac says

---

New commits:

c3df981	Trac #13441: refactored gcd to not use _gcd calls anymore
5b6e9c6	Trac #13628: refactored xgcd to not use _xgcd calls anymore.
861d698	Trac #13629: rings can provide _xgcd_univariate_polynomial for xgcd computations