Oculus Rift Adjustable Gun Stock w/ Magnets

###Updates:
#####9/2/19:
- Improved sling mounting point on Butt
- Added adjustable pin holes to Butt, Linkage 1, & Linkage 2 to prevent the joints from slipping
- Added Pin 3

###Summary:
Another addition to the list of Rift gun stocks to choose from on Thingiverse. I found that a lot of these other gun stocks weren't very adjustable besides being able to position where the controllers sit on the rail. I added multiple points of adjustment so the stock can work with multiple different