This adds a few settings to control global render quality, for faster renders when tweaking lighting etc. The implementation is not so great, and this should really be part of a proper render profile and preset system. So for now it's a hidden Peach feature, enabled by setting rt to 1. Before the next release, I'll either remove or improve it. Settings are: - Maximum subsurf level - Child particles percentage - Maximum shadow map samples - AO and SSS quality factor