Fixed possible race condition causing broken playback.
See: http://www.ps3mediaserver.org/forum/viewtopic.php?f=6&t=17193

Conflicts:
	CHANGELOG.txt
	src/main/java/net/pms/encoders/MEncoderVideo.java
	src/main/java/net/pms/encoders/MEncoderWebVideo.java
	src/main/java/net/pms/io/PipeIPCProcess.java
	src/main/java/net/pms/io/PipeProcess.java