cpp.js: add option to keep unknown preprocessor statements.
Shader: request OES_standard_derivatives, make sure the #extension statements reach the GLSL compiler.
Change alpha blending defaults to be with premultiplied alpha.
Entity: fix possible bug in GetCenter(), GetRadius() if the BB has never been requested before it is now calculated.
Renderer: update docs, make sure light statepools are reset every frame (otherwise there is infinite growth of heap consumption over time).
Add medea.CreateAABB API.
DirectionLight: add setter/getter for direction.
Node: clarify distinction between GetBB() and GetWorldBB(), make sure static BBs are always transformed to AABB.