Remove included Lua and LuaSocket source

Also rename README.txt to README.md and update it.

messages.lua

@@ -0,0 +1,13 @@
+-- This file is licensed under the terms of the BSD 2-clause license.
+-- See LICENSE.txt for details.
+
+mt_irc.msgs = mt_irc.lib.msgs
+
+function mt_irc:sendLocal(message)
+	minetest.chat_send_all(message)
+end
+
+function mt_irc:playerMessage(name, message)
+	return ("<%s> %s"):format(name, message)
+end
+