@shownames causes script warning/debug floater to misbehave

One effect of @shownames is to zap the from_id within parts of viewer received message processing. This causes problems in the script warning/debug floater since it uses the from_id to manage which panel the text should be displayed in, resulting in it getting displayed twice in the ALL messages panel

Fix - reverse the zapping of from_id if the message is of CHAT_TYPE_DEBUG_MSG