socketlock changes
streaminfo: unified streaminfo handling

- same stream data for demuxers and channelcache
- speedup of channels switching (with warm caches)
streaminfo: removed sendStreamInfo()
streaminfo: serialize stream information and persist channel cache
streaminfo: write channel cache in temp file before overwriting old cache file
protocol version 5

- also supports version 4
- added missing values from the XVDR_STREAM_CONTENTINFO message
  to XVDR_STREAM_CHANGE
- removed XVDR_STREAM_CONTENTINFO message
- added duration to XVDR_STREAM_MUXPKT
fixed info log entry
added XVDR_CHANNELSTREAM_SIGNAL message

- asynchronous request for signal information
- removed signal status query from the streamer's main loop
- do not send signal information if the live streamer is paused
- do not query signal information in timeshift mode (may block client requests)
build system changes for VDR 1.7.34