Projectkk2glider/simu audio

This pull has audio working (on Linux for now) in:
* radio/src/simu
* Companion simulator
* Standalone simulator

It uses PortAudio for sound output. This is widely used library and should work on Linux, Mac and Windows. Currently only Linux is working, I have not tried other OS-es. I think the source must be included/compiled for Windows and Mac versions. We could look how that is done in other projects that use this library, for example Audacity and Wireshark.

I prepared this against `master` branch, but I am not sure it should be included in master. So this pull is basically for development only and is not meant to be merged! Port to `next` should be very simple.

On Ubuntu/Debian based distributions one must install `libjack-jackd2-dev portaudio19-dev`, on Fedora (I believe) `portaudio-devel.i686`