0.6, Enjoy the Silence

Small update this week ! We now have a background musics, some sound effects and a audio settings tab in the options. It was also the occasion to notes a few possible improvements and bugs to fix later, as we come closer to the 1.0.

Added:
- Background music
- Sound effect on lots of stuff
- Audio settings in the options

Changed:
- UI tweaks to avoid unwanted quit when the level is cleared
- Better animation tracks on several small entities (loots, doors, etc)