Streamlined /me

Added the asterisk found in the "/me" command on the official Minecraft server implementation.

Replaced the for loop concatenating the message with a Lua function call to achieve the same effect with less code.

Completely redesigned the 'if' calls, to prevent unnecessary code from running.
You don't have to `remove` the first element, `table.concat` has an optional additional parameter specifying the first index where to start.