Move all commands to their own files

[joshcalafell]

Let's move commands such as batmansay and zeldasay to their own files, copying over what need to be copied in order to isolate them from main.s and terminal.s, which should be kept clean for our educational Skeleton OS. This will make things simpler for the person learning this and also make better use of what "should" be in a file like main.s