Synchronize audio when live streaming

[promi]

This can be a serious issue, in my previous attempts at writing a mixed mumble stream to a shoutcast server the buffer would overrun and the application would "leak" memory until it was oom-killed.

The current implementation of mumble-pluginbot-plusplus when sending audio from MPD to Mumble doesn't contain any clock synchronization / sample dropping / sample duplication / etc. mechanism to cope with this. (see also: http://stackoverflow.com/q/10638054/426242 ) This currently leads to noticable audio underruns.