Softer shadows (16 samples) + some assets

Brute force soft shadows with 16 samples from the shadow map.
Fixed the light matrix calculation. The ground does not cast shadows for
now, as it increases the shadow map precision.

Ivy "branch" asset and a blank small brick wall.
Fixed the windowed small brickwall's uv-map.
Merge branch 'master' of github.com:Maduiini/derelictfactory

Conflicts:
	assets/blend/scenes/test_scene.blend
	assets/scenes/test_scene.derscene
	render.cbp
Fixed pallet, some minor modifications