* Add integration test for bug #15340 This test case handles aligning rows with varying numbers of selections. A bug was found where things would become misaligned in this case. * Fix align_selections command The align selections command wouldn't line up properly when lines had different numbers of selections. The existing code was hard for me to understand with nested vecs and sorting. So I rewrote a large portion of the function body. Now there's two vecs without nested structure, so it should be more efficient and easier to reason about. It also fixes the bug, and rows with varying numbers of selections align.