Separate TEST.BAS into 3 separate programs

[jblang]

After I assembled my card, I wanted to do a quick test to verify that it was alive. I copied TEST.BAS and pasted it into MBASIC, not noticing it's actually 3 separate programs. The line numbers are the only clue that this is the case, and I wasn't paying close attention so I missed it. This made me question whether my sound card was working right because the program didn't do what it was supposed to, and I spent a lot of time scratching my head. Separating the programs into individual files would prevent someone else from making this mistake.

[electrified]

Thanks, have split the file and updated the readme.

[jblang]

Just noticed you have GPIO out and input examples backwards in the files you split out (i.e., the program does the opposite of what the filename indicates).

[electrified]

Whoops! Thanks, I've fixed.