Fixed bug in RecordingWaveFile.is_active property

darcs-hash:20090213155626-58103-939728474e7a45152905171a5c48618bc6b56305
Added ability to pause and resume a RecordingWaveFile

Added to RecordingWaveFile:
- pause() method
- resume() method
- is_paused read-only property

darcs-hash:20090213162353-58103-5fdc477981c0ec8ca99c06d1e81101700d241068