Hadley Spider, Davely mod

This is the metric curved-vane spider for the UTA of the [Hadley Telescope](https://kissner-optik.netlify.app/), modified with accommodations for the 18mm rods used in [Dave Aldritch's build](https://www.printables.com/model/638436-hadley-telescope-designbydave-mod). Also has pilot holes for M4 threaded inserts for the three collimation screws, and for the securing screws around the outside.