Generated terrain

Parts I implemented:

- Day and Night Cycle (procedural sky with worley noise, terrain coloring/lighting, interpolated horizon colors with sun and moon)

- Texturing and Texture Animation (assigned vertex data to uv coordinates of texture, separate VBOs for opaque vs. transparent blocks, animated lava and water blocks)

- Player Physics (wasd movements, acceleration, gravity, terrain collision using grid marching, adding and destroying blocks by ray casting gridMarch)