NACS Holster

This Thing is yet another NACS holster. It's based on cptskippy's design (https://www.thingiverse.com/thing:3272726), which in turn is based on others. I had a few specific features I wanted in a NACS holster, so I tweaked an earlier design to achieve them:

* Mounting holes to match those in a Clipper Creek EVSE's holster. I've replaced that EVSE with a NACS unit, but I wanted to avoid drilling more new holes than necessary in my wall.
* An inlet to the holster that's angled at 45 degrees to the wall. This reduces the amount of space that the NACS plug and cable stick out from the wall.
* Support for multiple manufacturers' plugs. Many non-Tesla NACS plugs, as well as even Tesla's J1772-to-NACS adapter, flare out after the tip of the NACS plug, and many holsters block these flared-out areas.
* Decent weatherproofing. My EVSE is mounted outside, so I wanted something that would do a better-than-average job of keeping snow and rain off the plug. This design's predecessor includes a "hoo