APU duty swap option

git-svn-id: http://nsfplay.googlecode.com/svn/trunk@98 98339eb9-417f-3607-c4bb-4869709a757b
fixed song wrap

git-svn-id: http://nsfplay.googlecode.com/svn/trunk@99 98339eb9-417f-3607-c4bb-4869709a757b