Documentation in Runtime 2.0

We expect to have full documentation for all public APIs in 2.0. The general 3D Studio documentation is also to be extended: document things that are not done or not fully compatible with 1.x, document things where the 2.0 runtime works but 1.x doesn't, and perhaps enhance the docs on a few features that are not really tested in 1.x but work fine in 2.0 (e.g. IBL, lightmaps, probes, etc.)