Fixed bug in resetting mPrevT1. That caused remaining issue noted in Bug 258 comments 2 and 3.
Moved call to UpdateMeters from TrackPanel::OnTimer() to audacityAudioCallback, where it calls gAudioIO->mOutputMeter->UpdateDisplay(), so the updates are synchronized with Meter Toolbar updates.
Removed unnecessary call to MixerBoard::UpdateMeters() in AudacityProject::UpdateMixerBoard().
Various cleanup.
Substantial changes to MixerTrackCluster::UpdateMeter() such that it now uses the original Meter::UpdateDisplay() rather than the override I wrote.
I think some of the ideas in the override were good though, mainly to use max and rms from blockfiles rather than passing interleaved sample buffer to Meter::UpdateDisplay() and having it recalculate those values. May be worth revisiting. Definitely worth testing for performance issues relative to 1.3.12.
Also, since all we're doing here is updating the meters, maybe we should remove it from TrackPanel::OnTimer() and do that in audacityAudioCallback where it calls gAudioIO->mOutputMeter->UpdateDisplay(). Thread issues?
