Fixed broken Nailer entity.

The Nailer was calling function CanNail incorrectly.
Fixed Adv. Duping the Grabber

It assumed the entity was within reach of the tracer when it was duping.
The opposite is often true.
Fixes: http://errors.garrysmod.com/error/3316845705/
Added a new line at end of file
Merge pull request #552 from DarkChowder/master

Fixed Nailer entity, and Fix for when the Grabber is being auto-duplicated