Add function to get info on a specific source to pulse wrapper
Use source instead of server info to get format for recording in pulse input

When setting up the capture, the plugin will now query pulse for the default
format of the specific source instead of the server.
This is useful if a source has different settings than what the defaults are
for the server, e.g. when the source is an output with 5.1 surround sound
and the microphone input is mono while the server defaults to stereo sound.
Simplify logging in pulse input

Use a macro to prefix debugging messages instead of prepending manually.
Small coding style fixes in pulse input
Log average latency in pulse input

This adds another statistics counter to the pulse plugin in order
to print the average latency reported by pulse when the source is
destroyed.
Merge pull request #261 from fryshorts/pulse-input

Use default source settings for recording in pulse input