Implement stable grothendieck polynomials for affine Weyl group elements in type A

[nthiery]

Patch under development on the Sage-Combinat queue:

http://combinat.sagemath.org/patches/file/tip/trac_11109-stable-grothendieck-polynomials-nt.patch

The current implementation currently gives incorrect results, due to a missuse of the Pieri factors. It will be fixed by adding another feature there.

CC: @sagetrac-sage-combinat @tscrim

Component: combinatorics

Keywords: affine weyl groups

Author: Nicolas M. Thiéry

Branch/Commit: public/ticket/11109 @ bdf2f59

Issue created by migration from https://trac.sagemath.org/ticket/11109

[nthiery]

Description changed:

--- 
+++ 
@@ -1 +1,5 @@
+Patch under development on the Sage-Combinat queue:
 
+http://combinat.sagemath.org/patches/file/tip/trac_11109-stable-grothendieck-polynomials-nt.patch
+
+The current implementation currently gives incorrect results, due to a missuse of the Pieri factors. It will be fixed by adding another feature there.