EMP tractor-beamed units

Issue: Units being tractor-beamed by GC still fire. Situation: GC stands under a T3 shield, tractors a brick, brick had shields in its priority, the brick kills the shield. Priority doesn't have to be set, these units don't necessarily target the GC.

I suggest to keep these units under EMP.

It's too antinoob: Can't have a defending GC under a T3 shield unless that shield is protected by another shield that doesn't have that GC under it

@melanol I don't understand why this is a bad outcome.