Low Profile battery holder (18650, AA, C, D etc)

I wanted a low profile 18650 holder (no back plate) to power my electric recliner chairs. There were some very good designs out there but they didn't quite suite my needs.

I took the design by enif and:

- Removed the back panel. This makes it lower profile and makes it easier to get the batteries in and out.

- Moved the holes in the spring end to the edges so that fatter multi-core wire can be wrapped around rather than poked through. (I needed high current)

- Smoothed off the sharp