Clearing unused vars

Commented out three unused vars and restored in comment a removed usage
of one for future reference/use.
Follow restoration

Restores observer follow to original targetting method using getmobs().

This will likely remove follow from the right-click menu, but is the
cleanest way to produce a sorted list when follow is clicked, and
double-clicking any mob will follow that mob.

I've also left a comment block containing some experimental code I
couldn't make work. Take a crack at it if you like.