Include bb2 vs ab2 vs ab3

[Daedalus]

I think the AmiBlitz2 includes still had the .bb2 extension, but in general you should use the ones for the version of Blitz you're using. Later includes would be better, but many use features of AmiBlitz3 that aren't available in Blitz 2.1 so you'll probably have trouble compiling them under earlier versions.