v 0.3 from player feedback now online

As I said in the original description - this game did not undergo heavy testing. So I am glad to have gotten some more feedback from friends - thanks again to everyone that took their time to give me feedback, you rock!

One thing that became apparent is that my testing environment, an old, beaten up PC with equally old screens, seems to have made me underestimate exactly how dark the game gets on screens with better color and brightness dynamics and the ability to display better blackness. So an important addition has been added: The ability to adjust how dark the level actually is. Adjust to your liking, but try not to cheat yourself out of a tense experience.

All changes borne from feedback in CHANGELOG.txt and also here:

 - Included settings to adjust darkness in settings menu
 - Added visual indicator to grenade explosion radius
 - Significantly reduced turret health
 - Added "restore default settings" button to settings screen