Replaced PJSIPUA.play_wav_file() method with instancable WaveFile that includes support for looping with abritrary pause intervals and an event to indicate that playing is done

darcs-hash:20090209153930-58103-a57d49c9f0e306c02322d7097ce3ec0f08d795a5
Made RecordingWaveFile class instancable and remove PJSIPUA.rec_wav_file() method, to make the interface consistent with WaveFile

darcs-hash:20090211154437-58103-88c0c5f0560ff5ec99e3a20216f2aba0b9ab36ce