New main menu headers + logoff header + news header

Say goodbye to the old main menu header! Here you go, two main menu headers that are randomly displayed. A huge leap forward for the x84 project.

	new file:   art/main1.asc
        new file:   art/main2.asc
	modified:   main.py
There is no need for this, showart already provides it.

Simply showart('art/main*.asc')