/kill can't be used by non-ops

The suicide "/kill" command does not work for players who are not op. In some cases this is the only way to get one's self out of certain situations, and I find it quite useful.

This command has often gone back and forth between op-only and not op-only, I think when this bug is fixed a comment needs to be left somewhere in the code to make sure this doesn't keep happening.

**NOTE:** The /kill command does NOT take a parameter, it can NOT be used to kill other players, it always kills the person who types it.