Add interface to nauty-gentreeg (generator of trees)

[dcoudert]

Add interface to Nauty's gentreeg generator of non-isomorphic trees.

It is slower than graphs.trees() but has more options.

Component: graph theory

Author: David Coudert

Branch: 7a5e122

Reviewer: Frédéric Chapoton

Issue created by migration from https://trac.sagemath.org/ticket/33670

[dcoudert]

Branch: public/graphs/33670_gentreeg

[dcoudert]

New commits:

077a46f

trac #33670: add interface to nauty's gentreeg

[dcoudert]

Commit: 077a46f

[fchapoton]

comment:2

typo "aggrees"

[sagetrac-git]

Changed commit from 077a46f to 7a5e122

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

7a5e122

trac #33670: fix typo

[dcoudert]

comment:4

fixed.

[fchapoton]

comment:5

feu vert