FIX: Casting Translocate on a non-grouped player = crash

[Derision]

If a player tries to translocate another player who is not grouped,
zone will crash and the server becomes unusable.

There is no check if the spell target is grouped, and if not, SIGSEGV.

In spells.cpp, around line 2013, in case SE_Translocate:

After:

if(IsClient())
{
Group* group = entity_list.GetGroupByClient(this->CastToClient());

Add:

if(!group) {
	Message(13, "You must be grouped with the caster to be translocated.");
	break;
}