New physics, networking overhaul

Soooo...... I finally decided to add some more depth to physics, so I
instantly deleted all my "attemts" to make physics and replaced it with
open source library Farseer Physics. Why I choosed FEP over Box2D?
Becouse Box2D port to .NET called Box2DX is totally outdated. Also, now
SpriteBatch can handle SpriteBatch stacking (so you can run another
SpriteBatch within SpriteBatch). And, I increased performance of light
engine by using SpriteBatch for drawing lights. Hopefully that´s all for
now :)