Vive Rifle Rear Controller with Strap Cutout

Print vive-rifle-rear-controller-strap.stl, the other .stl files are used to build vive-rifle-rear-controller-strap.stl.

Adds a cutout for the controller strap so it's not pinched by the rear controller holder.

When using the Rifle controller I remove the controller strap so it doesn't get pinched. I'm not sure if it would get broken, but I don't want to risk it.

This means that I have to take time to connect or disconnect the strap when I switch games.

This mod leaves plenty of spac