support playback natively on I9505
Merge remote-tracking branch 'origin/master'
organize import
Merge remote-tracking branch 'origin/master'
on I9505, recording can be done through AudioRecord API, but only when
both uplink and downlink voice are included
Merge remote-tracking branch 'origin/master'
correct the AUDIO_DEVICE_IN_WIRED_HEADSET enum value on different
versions of Android OS
Mute the built-in Mic in both Caller and Answerer mode to prevent the
VQT from polluted by the background noise
consolidate the device support across different phone model and OS
version. Now by default, native playback and recording will be tried out
first. If the device doesn't require any native intervention, it falls
back to the high level Android API.

I9305 no longer requires any native intervention.
Merge branch 'fta1.31'
Merge branch 'fta1.31'
move handling of caller's call state change into a separate thread so
that when the caller is waiting for the answerer to pickup the call, the
main UI thread is not blocked