Add new command /wrtoggle in plugin.yml

Will implement it soon.
Small code optimizations

Sends a message with the location of a sign linked with a channel which
doesn't exist.
Directly return instead of turning on the channel if it's locked.
Start implementing /Wr activate

Yes I renamed the command to /wr activate
Created the permission node wirelessredstone.commands.activate
Added the command method into WirelessCommands class.
Set executor in the main class.