Vg

- Add `vg.shape.columnize()`, a helper function for functions which may,
accept and return a stack of points or a single point.
- Add `vg.shape.check_value_any()` for checking an input against multiple
valid shape.
- Fix `vg.euclidean_distance()` so it will correctly accept a single point
as the first argument with a stack of points as the second argument.
- Correct many erroneous mentions of `3x1` and `kx1` in the documentation
and error messages.

- Add `vg.average()`.
- `vg.apex()`: Return a copy instead of a view.
- Improve documentation intro.
- Distribute universal wheels.

- Fix `vg.nearest()` and `vg.farthest()` with `ret_index=False`

- Allow `vg.scale_factor()` to accept a mix of stacked and unstacked inputs.

- Add `vg.nearest()`.
- Add `vg.scale_factor()`.
- Add `vg.orient()`.
- Improve documentation, including docs for `vg.almost_collinear()`.

- `vg.scalar_projection` and `vg.project`: Allow stacked inputs for `onto` when
`vector` is also stacked.