Removing old line

I prefer [receiver]
Also, with the incoming of the inverter and delayer, it's needed to show
that a regular sign is regular by putting [default] on the third line.
I need to make the debug mode less... verbose

No seriously, that line could put a server offline by crashing, because
it was puttin a lot of messages in the debug mode. Imagine, there are a
lot of chunks which are prevented from unloading for ONE sign, so on a
big server... that creates a lot of messages, and the logs become messy.
I have able to see it on Kervinou's server.