removed tracker from the lazyvalues package. access to tracker
information is now done through a "borrow" function
moved volume change logic from win_tracker to main tracker package
AudioTick() function in tracker interface accepts TrackerEnvironment
instance. tracker implementation differentiates emulation instances and
records AudioTick() information accordingly
better visuals for tracker window
sketched in idea for a tracker "replay" feature that will allow a
selection of audio output to be replayed. it works in principal but is
not currently used
the emulation package has been unecessary since the amalgamation of the
debugger and play modes. in order to allow switching between the two
modes it was necessary to remove the playmode package and to move all
playmode loops and other considerations into the debugger package. as a
result the abstraction offered by the emulation package is uncessary
this means that playmode now uses the lazy system. it's only loading
what it needs so as not to use too much memory. the good news is that it
doesn't seem to take any significant CPU time
tracker reset on debugger/emulation reset
piano keys window is now part of the tracker window
updated README indicating new hotkey
