accepttp should not include mob tp requests via group

[Alan Glover]

Some people don't get that sending a tp request to a group of friends is bordering on the anti-social, and the potential for a nearly-naked RPer landing in the middle of a vanilla event is embarrassing for all concerned. Accordingly, I am proposing that @accepttp=add is changed so that it does not auto accept mass group tps (assuming there is some way to distinguish these from a one-to-one tplure).

Since there may be some legitmate users of this, an additional new command such as @acceptgrouptp could be define which when unset permits current behaviour but when set (=n) blocks group tp requests.