Add option to build without sound (default sound on)

[scivision]

To help development and debugging as well as use on systems without sound hardware or sound libraries, enable option to build without sound on Windows, MacOS, Linux and similar. By default, the sound is on as before. This was implemented by cut/paste the sound-relevant parts of spec_win.cpp to win_sound.cpp and spec_nix.cpp to pulse_audio.cpp. When sound is not enabled, the definitions are stubbed in to allow building without using them in sound_stub.cpp. Makefile and build.sh were updated to add pulse_audio.cpp.

Also, changed conf.[h,cpp] to have Unix style line endings like the rest of the project source code files.