audio: blocking audio player.

Links and requires libsdnfile (for WAVs) and pulseaudio (playback).
Much hardcoded still
audio: nonblocking play_sound.
audio: fix userdata passing.
main: try to play given cl argument.
audio: Oops.. typofix
Merge pull request #10 from leomuona/master

motors design added
Merge pull request #9 from jesseniemisto/master

nonblocking audio player.
requirements and design: paragraph about audio on software side.
Merge pull request #11 from jesseniemisto/master

requirements and design: paragraph about audio on software side.
Few random fixes.
Remote control general structure.
Merge pull request #12 from jesseniemisto/master

Few random fixes.
Merge branch 'master' into remote_control
Added remote control terminating and reconnect.
Fixed looping networking come when client interrupts to connection.
Changed remote port from 555 to 5555.
gpio functions for pins