Grapple hook needs a blocker

[Malcolmnixon]

Currently the grapple hook target only collides with layers selected for grappling. The result is that it's possible to shoot "through" an object that isn't grappleable and hit an object behind it.

Instead there should be two masks - one for what objects the grapple-target collides with, and another specifying which objects are valid grapple-targets