Add a 'clean' target to Makefile
Upgrade to Pepper API v23

The plugin compiles and runs under the current stable version of the
Pepperl API (v23). Indicate this in the README file.
Correct usage of string comparison function
Eliminate init_xz() function

Rather than require the client app to explicitly initialize the Embedded
XZ library, just check whether the library has been initialized whenever
performing a decompression operation. I have been bitten by this too
many times and it's not a huge performance consideration.
Linux/PulseAudio command line testbench utility

This testbench utility ('pulse-testbench') uses the same infrastructure
as the main saltygme module but outputs the audio through the Linux
PulseAudio API. Ideally, this will help prototype new music engines to
add to the system and should also be very useful for debugging.