Define a sparse bitset structure

[kliem]

This structure is a copy of bitset_t for now and at the moment mainly illustrates that the entire setup with a fused type in biteset.pxi works.

After combinatorial polyhedron uses this type for its atom-representation it should contain some additional information about which limbs are relevant. So it will increase slightly in memory usage, while still using constant memory (dependent on size). However, access to non-zero limbs will be improved.

Depends on #30572
Depends on #30596

CC: @tscrim

Component: cython

Keywords: sparse bitset

Author: Jonathan Kliem

Branch/Commit: 9d3ebc7

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/30597

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. This was a forced push. New commits:

9d3ebc7

define sparse_bitset_t

[sagetrac-git]

Changed commit from 2f2b73f to 9d3ebc7

[tscrim]

comment:4

LGTM.

[tscrim]

Reviewer: Travis Scrimshaw

[kliem]

comment:5

Thank you.

[vbraun]

Changed branch from u/gh-kliem/sparse_bitsets_via_fuzed_types to 9d3ebc7