This is a combination of 4 commits. Original commit messages follow.
[PD] Initial support for point sections in loft
This commit allows the last section in a loft to be a single vertex of a solid.
Currently single vertices of sketches or datum points are NOT supported.
[PD] Allow loft "profiles" to be points
Most reliably done in dialog-based workflow.
[PD] Allow loft last section to be sketch point
[PD] Refactor `Loft::execute`
Makes it easier to support adding a single-vertex sketch in profile or sections
field when selecting the sketch in tree (i.e. without selecting subelements).
[PD] Refactoring after PR #5176 is merged
d99bc1e9df