Small improvements for `FaceIterator_base`

[kliem]

This ticket collects some small improvements for the the class FaceIterator_base and the inherited classes FaceIterator, FaceIterator_geom:

• Add a method reset.

• Add a method current that retrieves the last value of __next__.

• Simplify the methods ignore_subfaces and ignore_supfaces by outsourcing the common code to ignore_subsets.

  Follow up:

  Use face iterator to obtain the meet of (some) vertices or the join of (some) facets.

Depends on #29654

CC: @jplab @LaisRast

Component: geometry

Keywords: polyhedron, face iterator

Author: Jonathan Kliem

Branch/Commit: fc84ffa

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/29681

[kliem]

Branch: public/29681

[kliem]

Commit: f6633bd

[kliem]

Last 10 new commits:

53fd2a2	fixed failing doctest
a6d2b2d	a face iterator subclass that yield PolyhedronFace
1476675	representation like Polyhedron_base
47fc7cd	account for FaceIterator -> FaceIterator_base
295039a	documentation
d36da4a	coverage and small improvement
2d0f0d9	method `reset` for the face iterator
6d99a4c	typo
5711f6b	method `ignore_subsets`
f6633bd	method current and fix for reset

[mkoeppe]

comment:3

needs rebase

[kliem]

New commits:

3f92d2d	fixed merge conflict
3ba34fd	move documenation to exposed class
d89a503	Merge branch 'public/29654-reb3' of git://trac.sagemath.org/sage into public/29681-reb
fc84ffa	Merge branch 'public/29681' of git://trac.sagemath.org/sage into public/29681-reb

[kliem]

Changed commit from f6633bd to fc84ffa

[kliem]

Changed branch from public/29681 to public/29681-reb