Implementation of class for cores

[anneschilling]

This patch implements a class for cores and methods associated to them.

---

Apply attachment: trac_11742-cores-as.patch

Depends on #11700
Depends on #10530

CC: @sagetrac-sage-combinat

Component: combinatorics

Keywords: cores, partitions

Author: Anne Schilling, Mike Zabrocki

Reviewer: Nicolas Thiery, Mike Zabrocki

Merged: sage-4.8.alpha0

Issue created by migration from https://trac.sagemath.org/ticket/11742

[anneschilling]

Dependencies: #11700

[anneschilling]

Reviewer: Nicolas Thiery, Mike Zabrocki

[anneschilling]

comment:4

The patch is ready for review. Nicolas already gave a lot of advice on the design and wrote a review patch, which has been incorporated in the posted patch.

[anneschilling]

Description changed:

--- 
+++ 
@@ -1 +1,3 @@
 This patch implements a class for cores and methods associated to them.
+
+Apply [attachment: trac_11742-cores-as.patch](https://github.com/sagemath/sage-prod/files/10653545/trac_11742-cores-as.patch.gz)

[anneschilling]

Changed dependencies from #11700 to #11700, #10530

[anneschilling]

Description changed:

--- 
+++ 
@@ -1,3 +1,5 @@
 This patch implements a class for cores and methods associated to them.
 
+---
+
 Apply [attachment: trac_11742-cores-as.patch](https://github.com/sagemath/sage-prod/files/10653545/trac_11742-cores-as.patch.gz)

[zabrocki]

comment:8

Everything that I ask for was addressed. Thanks Anne! Chris and I were using this code just yesterday and found it super useful. I double checked that the transpositions were on the correct side :

sage: c = Core([11,8,5,5,3,3,1,1,1],4)
sage: c.affine_symmetric_group_action([2,5],transposition=True)
[11, 8, 7, 6, 5, 4, 3, 2, 1]

which agrees with Example 9.6 of LLMS - Affine Insertion paper

[anneschilling]

Attachment: trac_11742-cores-as.patch.gz