[sound_play] add replace arg in sendMsg

[knorth55]

I add replace argument in sendMsg.

when replace is true, SoundClient replace the audio commands. (default)
when replace is false, SoundClient waits until previous commands finish.

cc. @708yamaguchi

[knorth55]

@708yamaguchi have you done checking this feature?

[708yamaguchi]

Yes, thank you.

I checked that replace=False works nicely.
SoundClient can wait for other nodes to finish speaking.