libcore|Vector: Decomposing a Vector4 into an array
Refactor|Client|Renderer: Common parameters of vissprites

This is the first step toward more object-oriented vissprites. The
common parameters (positioning and lighting) were moved to the main
vissprite_s struct as VisEntityPose and VisEntityLighting. Eventually
vissprites should form a class hierarchy that then provides methods
for setting up and drawing the entity via a base class.