Updated typewriter key stitch markers

This is a much needed update to the original typewriter keys stitch markers. The old file was a mess, and I needed to clean it up, and it's been years since I've used Fusion360.
Updates are:
-stitch markers are now closed, and not open. I found that the ones with the slots were often falling off. The old design will remain up if you want the open type.
-separate files! Now you can pick out individual ones or only print some.
-slightly smaller needle hole. it is now about 9mm.

The file is still somewhat of a mess, but if there's enough interest I could make larger/smaller versions (or just print them at a larger % size), and separate files for the open versions.